diff --git a/source/blender/asset_system/intern/asset_essentials_library.cc b/source/blender/asset_system/intern/asset_essentials_library.cc
index 8ae0d6c39dc..8afbe063e5b 100644
--- a/source/blender/asset_system/intern/asset_essentials_library.cc
+++ b/source/blender/asset_system/intern/asset_essentials_library.cc
@@ -17,11 +17,9 @@ namespace blender::asset_system {
 StringRefNull essentials_directory_path()
 {
   static std::string path = []() {
-    const char *datafiles_path = BKE_appdir_folder_id(BLENDER_DATAFILES, "assets");
-    if (datafiles_path == nullptr) {
-      return "";
-    }
-    return datafiles_path;
+    const std::optional<std::string> datafiles_path = BKE_appdir_folder_id(BLENDER_DATAFILES,
+                                                                           "assets");
+    return datafiles_path.value_or("");
   }();
   return path;
 }
diff --git a/source/blender/blenfont/intern/blf_font_default.cc b/source/blender/blenfont/intern/blf_font_default.cc
index 7a4454c46ed..eabc8f2ecfe 100644
--- a/source/blender/blenfont/intern/blf_font_default.cc
+++ b/source/blender/blenfont/intern/blf_font_default.cc
@@ -23,8 +23,9 @@
 
 static int blf_load_font_default(const char *filename, const bool unique)
 {
-  const char *dir = BKE_appdir_folder_id(BLENDER_DATAFILES, BLF_DATAFILES_FONTS_DIR);
-  if (dir == nullptr) {
+  const std::optional<std::string> dir = BKE_appdir_folder_id(BLENDER_DATAFILES,
+                                                              BLF_DATAFILES_FONTS_DIR);
+  if (!dir.has_value()) {
     fprintf(stderr,
             "%s: 'fonts' data path not found for '%s', will not be able to display text\n",
             __func__,
@@ -33,7 +34,7 @@ static int blf_load_font_default(const char *filename, const bool unique)
   }
 
   char filepath[FILE_MAX];
-  BLI_path_join(filepath, sizeof(filepath), dir, filename);
+  BLI_path_join(filepath, sizeof(filepath), dir->c_str(), filename);
 
   return (unique) ? BLF_load_unique(filepath) : BLF_load(filepath);
 }
@@ -55,18 +56,15 @@ int BLF_load_mono_default(const bool unique)
 static void blf_load_datafiles_dir()
 {
   const char *datafiles_fonts_dir = BLF_DATAFILES_FONTS_DIR SEP_STR;
-  const char *path = BKE_appdir_folder_id(BLENDER_DATAFILES, datafiles_fonts_dir);
-  if (UNLIKELY(!path)) {
+  const std::optional<std::string> path = BKE_appdir_folder_id(BLENDER_DATAFILES,
+                                                               datafiles_fonts_dir);
+  if (!path.has_value()) {
     fprintf(stderr, "Font data directory \"%s\" could not be detected!\n", datafiles_fonts_dir);
     return;
   }
-  if (UNLIKELY(!BLI_exists(path))) {
-    fprintf(stderr, "Font data directory \"%s\" does not exist!\n", path);
-    return;
-  }
 
   direntry *file_list;
-  uint file_list_num = BLI_filelist_dir_contents(path, &file_list);
+  uint file_list_num = BLI_filelist_dir_contents(path->c_str(), &file_list);
   for (int i = 0; i < file_list_num; i++) {
     if (S_ISDIR(file_list[i].s.st_mode)) {
       continue;
diff --git a/source/blender/blenkernel/BKE_appdir.hh b/source/blender/blenkernel/BKE_appdir.hh
index 7f8a8776657..528cb849b6e 100644
--- a/source/blender/blenkernel/BKE_appdir.hh
+++ b/source/blender/blenkernel/BKE_appdir.hh
@@ -12,6 +12,9 @@
 
 #include <stddef.h>
 
+#include <optional>
+#include <string>
+
 #include "BLI_compiler_attrs.h"
 
 struct ListBase;
@@ -76,25 +79,26 @@ bool BKE_appdir_folder_id_ex(int folder_id,
                              const char *subfolder,
                              char *path,
                              size_t path_maxncpy);
-const char *BKE_appdir_folder_id(int folder_id, const char *subfolder) ATTR_WARN_UNUSED_RESULT;
+std::optional<std::string> BKE_appdir_folder_id(int folder_id,
+                                                const char *subfolder) ATTR_WARN_UNUSED_RESULT;
 /**
  * Returns the path to a folder in the user area, creating it if it doesn't exist.
  */
-const char *BKE_appdir_folder_id_create(int folder_id,
-                                        const char *subfolder) ATTR_WARN_UNUSED_RESULT;
+std::optional<std::string> BKE_appdir_folder_id_create(int folder_id, const char *subfolder)
+    ATTR_WARN_UNUSED_RESULT;
 /**
  * Returns the path to a folder in the user area without checking that it actually exists first.
  */
-const char *BKE_appdir_folder_id_user_notest(int folder_id,
-                                             const char *subfolder) ATTR_WARN_UNUSED_RESULT;
+std::optional<std::string> BKE_appdir_folder_id_user_notest(int folder_id, const char *subfolder)
+    ATTR_WARN_UNUSED_RESULT;
 /**
  * Returns the path of the top-level version-specific local, user or system directory.
  * If check_is_dir, then the result will be NULL if the directory doesn't exist.
  */
-const char *BKE_appdir_resource_path_id_with_version(int folder_id,
-                                                     bool check_is_dir,
-                                                     int version);
-const char *BKE_appdir_resource_path_id(int folder_id, bool check_is_dir);
+std::optional<std::string> BKE_appdir_resource_path_id_with_version(int folder_id,
+                                                                    bool check_is_dir,
+                                                                    int version);
+std::optional<std::string> BKE_appdir_resource_path_id(int folder_id, bool check_is_dir);
 
 /**
  * Check if this is an install with user files kept together
diff --git a/source/blender/blenkernel/intern/appdir.cc b/source/blender/blenkernel/intern/appdir.cc
index b61f4d0e97f..e0f63b147df 100644
--- a/source/blender/blenkernel/intern/appdir.cc
+++ b/source/blender/blenkernel/intern/appdir.cc
@@ -685,19 +685,20 @@ bool BKE_appdir_folder_id_ex(const int folder_id,
   return true;
 }
 
-const char *BKE_appdir_folder_id(const int folder_id, const char *subfolder)
+std::optional<std::string> BKE_appdir_folder_id(const int folder_id, const char *subfolder)
 {
-  static char path[FILE_MAX] = "";
+  char path[FILE_MAX] = "";
   if (BKE_appdir_folder_id_ex(folder_id, subfolder, path, sizeof(path))) {
     return path;
   }
-  return nullptr;
+  return std::nullopt;
 }
 
-const char *BKE_appdir_folder_id_user_notest(const int folder_id, const char *subfolder)
+std::optional<std::string> BKE_appdir_folder_id_user_notest(const int folder_id,
+                                                            const char *subfolder)
 {
   const int version = BLENDER_VERSION;
-  static char path[FILE_MAX] = "";
+  char path[FILE_MAX] = "";
   const bool check_is_dir = false;
 
   switch (folder_id) {
@@ -739,15 +740,13 @@ const char *BKE_appdir_folder_id_user_notest(const int folder_id, const char *su
   }
 
   if ('\0' == path[0]) {
-    return nullptr;
+    return std::nullopt;
   }
   return path;
 }
 
-const char *BKE_appdir_folder_id_create(const int folder_id, const char *subfolder)
+std::optional<std::string> BKE_appdir_folder_id_create(const int folder_id, const char *subfolder)
 {
-  const char *path;
-
   /* Only for user folders. */
   if (!ELEM(folder_id,
             BLENDER_USER_DATAFILES,
@@ -756,26 +755,26 @@ const char *BKE_appdir_folder_id_create(const int folder_id, const char *subfold
             BLENDER_USER_AUTOSAVE))
   {
     BLI_assert_unreachable();
-    return nullptr;
+    return std::nullopt;
   }
 
-  path = BKE_appdir_folder_id(folder_id, subfolder);
+  std::optional<std::string> path = BKE_appdir_folder_id(folder_id, subfolder);
 
-  if (!path) {
+  if (!path.has_value()) {
     path = BKE_appdir_folder_id_user_notest(folder_id, subfolder);
-    if (path) {
-      BLI_dir_create_recursive(path);
+    if (path.has_value()) {
+      BLI_dir_create_recursive(path->c_str());
     }
   }
 
   return path;
 }
 
-const char *BKE_appdir_resource_path_id_with_version(const int folder_id,
-                                                     const bool check_is_dir,
-                                                     const int version)
+std::optional<std::string> BKE_appdir_resource_path_id_with_version(const int folder_id,
+                                                                    const bool check_is_dir,
+                                                                    const int version)
 {
-  static char path[FILE_MAX] = "";
+  char path[FILE_MAX] = "";
   bool ok;
   switch (folder_id) {
     case BLENDER_RESOURCE_PATH_USER:
@@ -793,10 +792,14 @@ const char *BKE_appdir_resource_path_id_with_version(const int folder_id,
       BLI_assert_msg(0, "incorrect ID");
       break;
   }
-  return ok ? path : nullptr;
+  if (!ok) {
+    return std::nullopt;
+  }
+  return path;
 }
 
-const char *BKE_appdir_resource_path_id(const int folder_id, const bool check_is_dir)
+std::optional<std::string> BKE_appdir_resource_path_id(const int folder_id,
+                                                       const bool check_is_dir)
 {
   return BKE_appdir_resource_path_id_with_version(folder_id, check_is_dir, BLENDER_VERSION);
 }
@@ -964,11 +967,13 @@ bool BKE_appdir_program_python_search(char *program_filepath,
   SNPRINTF(python_version, "%s%d.%d", basename, version_major, version_minor);
 
   {
-    const char *python_bin_dir = BKE_appdir_folder_id(BLENDER_SYSTEM_PYTHON, "bin");
-    if (python_bin_dir) {
+    const std::optional<std::string> python_bin_dir = BKE_appdir_folder_id(BLENDER_SYSTEM_PYTHON,
+                                                                           "bin");
+    if (python_bin_dir.has_value()) {
 
       for (int i = 0; i < ARRAY_SIZE(python_names); i++) {
-        BLI_path_join(program_filepath, program_filepath_maxncpy, python_bin_dir, python_names[i]);
+        BLI_path_join(
+            program_filepath, program_filepath_maxncpy, python_bin_dir->c_str(), python_names[i]);
 
         if (
 #ifdef _WIN32
diff --git a/source/blender/blenkernel/intern/blendfile.cc b/source/blender/blenkernel/intern/blendfile.cc
index d795bc15ad9..e043de4c7de 100644
--- a/source/blender/blenkernel/intern/blendfile.cc
+++ b/source/blender/blenkernel/intern/blendfile.cc
@@ -1271,13 +1271,13 @@ bool BKE_blendfile_userdef_write_app_template(const char *filepath, ReportList *
 bool BKE_blendfile_userdef_write_all(ReportList *reports)
 {
   char filepath[FILE_MAX];
-  const char *cfgdir;
+  std::optional<std::string> cfgdir;
   bool ok = true;
   const bool use_template_userpref = BKE_appdir_app_template_has_userpref(U.app_template);
 
   if ((cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr))) {
     bool ok_write;
-    BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_USERPREF_FILE);
+    BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_USERPREF_FILE);
 
     printf("Writing userprefs: \"%s\" ", filepath);
     if (use_template_userpref) {
@@ -1304,7 +1304,7 @@ bool BKE_blendfile_userdef_write_all(ReportList *reports)
   if (use_template_userpref) {
     if ((cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, U.app_template))) {
       /* Also save app-template preferences. */
-      BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_USERPREF_FILE);
+      BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_USERPREF_FILE);
 
       printf("Writing userprefs app-template: \"%s\" ", filepath);
       if (BKE_blendfile_userdef_write(filepath, reports) != 0) {
diff --git a/source/blender/blenkernel/intern/studiolight.cc b/source/blender/blenkernel/intern/studiolight.cc
index e6bf183534a..4d5470ac2d3 100644
--- a/source/blender/blenkernel/intern/studiolight.cc
+++ b/source/blender/blenkernel/intern/studiolight.cc
@@ -609,13 +609,13 @@ static void studiolight_add_files_from_datafolder(const int folder_id,
                                                   const char *subfolder,
                                                   int flag)
 {
-  const char *folder = BKE_appdir_folder_id(folder_id, subfolder);
+  const std::optional<std::string> folder = BKE_appdir_folder_id(folder_id, subfolder);
   if (!folder) {
     return;
   }
 
   direntry *dirs;
-  const uint dirs_num = BLI_filelist_dir_contents(folder, &dirs);
+  const uint dirs_num = BLI_filelist_dir_contents(folder->c_str(), &dirs);
   int i;
   for (i = 0; i < dirs_num; i++) {
     if (dirs[i].type & S_IFREG) {
diff --git a/source/blender/blentranslation/intern/blt_lang.cc b/source/blender/blentranslation/intern/blt_lang.cc
index e0546f42504..6da6d929aa8 100644
--- a/source/blender/blentranslation/intern/blt_lang.cc
+++ b/source/blender/blentranslation/intern/blt_lang.cc
@@ -65,16 +65,18 @@ static void free_locales()
 
 static void fill_locales()
 {
-  const char *const languages_path = BKE_appdir_folder_id(BLENDER_DATAFILES, "locale");
+  std::optional<std::string> languages_path = BKE_appdir_folder_id(BLENDER_DATAFILES, "locale");
   char languages[FILE_MAX];
-  LinkNode *lines = nullptr, *line;
+  LinkNode *lines = nullptr, *line = nullptr;
   char *str;
   int idx = 0;
 
   free_locales();
 
-  BLI_path_join(languages, FILE_MAX, languages_path, "languages");
-  line = lines = BLI_file_read_as_lines(languages);
+  if (languages_path.has_value()) {
+    BLI_path_join(languages, FILE_MAX, languages_path->c_str(), "languages");
+    line = lines = BLI_file_read_as_lines(languages);
+  }
 
   /* This whole "parsing" code is a bit weak, in that it expects strictly formatted input file...
    * Should not be a problem, though, as this file is script-generated! */
@@ -181,7 +183,7 @@ EnumPropertyItem *BLT_lang_RNA_enum_properties()
 void BLT_lang_init()
 {
 #ifdef WITH_INTERNATIONAL
-  const char *const messagepath = BKE_appdir_folder_id(BLENDER_DATAFILES, "locale");
+  const std::optional<std::string> messagepath = BKE_appdir_folder_id(BLENDER_DATAFILES, "locale");
 #endif
 
 /* Make sure LANG is correct and wouldn't cause #std::runtime_error. */
@@ -212,8 +214,8 @@ void BLT_lang_init()
 #endif
 
 #ifdef WITH_INTERNATIONAL
-  if (messagepath) {
-    bl_locale_init(messagepath, TEXT_DOMAIN_NAME);
+  if (messagepath.has_value()) {
+    bl_locale_init(messagepath->c_str(), TEXT_DOMAIN_NAME);
     fill_locales();
   }
   else {
diff --git a/source/blender/editors/interface/interface_icons.cc b/source/blender/editors/interface/interface_icons.cc
index dc8c0115adc..15ea1a832de 100644
--- a/source/blender/editors/interface/interface_icons.cc
+++ b/source/blender/editors/interface/interface_icons.cc
@@ -950,11 +950,11 @@ static void init_internal_icons()
 {
 #  if 0 /* temp disabled */
   if ((btheme != nullptr) && btheme->tui.iconfile[0]) {
-    char *icondir = BKE_appdir_folder_id(BLENDER_DATAFILES, "icons");
+    std::optional<std::string> icondir = BKE_appdir_folder_id(BLENDER_DATAFILES, "icons");
     char iconfilestr[FILE_MAX];
 
-    if (icondir) {
-      BLI_path_join(iconfilestr, sizeof(iconfilestr), icondir, btheme->tui.iconfile);
+    if (icondir.has_value()) {
+      BLI_path_join(iconfilestr, sizeof(iconfilestr), icondir->c_str(), btheme->tui.iconfile);
 
       /* if the image is missing bbuf will just be nullptr */
       bbuf = IMB_loadiffname(iconfilestr, IB_rect, nullptr);
@@ -1054,14 +1054,14 @@ static void init_internal_icons()
 static void init_iconfile_list(ListBase *list)
 {
   BLI_listbase_clear(list);
-  const char *icondir = BKE_appdir_folder_id(BLENDER_DATAFILES, "icons");
+  const std::optional<std::string> icondir = BKE_appdir_folder_id(BLENDER_DATAFILES, "icons");
 
-  if (icondir == nullptr) {
+  if (!icondir.has_value()) {
     return;
   }
 
   direntry *dir;
-  const int totfile = BLI_filelist_dir_contents(icondir, &dir);
+  const int totfile = BLI_filelist_dir_contents(icondir->c_str(), &dir);
 
   int index = 1;
   for (int i = 0; i < totfile; i++) {
@@ -1078,7 +1078,7 @@ static void init_iconfile_list(ListBase *list)
         /* check to see if the image is the right size, continue if not */
         /* copying strings here should go ok, assuming that we never get back
          * a complete path to file longer than 256 chars */
-        BLI_path_join(iconfilestr, sizeof(iconfilestr), icondir, filename);
+        BLI_path_join(iconfilestr, sizeof(iconfilestr), icondir->c_str(), filename);
         bbuf = IMB_loadiffname(iconfilestr, IB_rect);
 
         if (bbuf) {
diff --git a/source/blender/editors/interface/interface_string_search.cc b/source/blender/editors/interface/interface_string_search.cc
index 06aaff74d61..9bb31809899 100644
--- a/source/blender/editors/interface/interface_string_search.cc
+++ b/source/blender/editors/interface/interface_string_search.cc
@@ -52,12 +52,14 @@ const RecentCache *get_recent_cache_or_null()
 
 static std::optional<std::string> get_recent_searches_file_path()
 {
-  const char *user_config_dir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr);
-  if (!user_config_dir) {
+  const std::optional<std::string> user_config_dir = BKE_appdir_folder_id_create(
+      BLENDER_USER_CONFIG, nullptr);
+  if (!user_config_dir.has_value()) {
     return std::nullopt;
   }
   char filepath[FILE_MAX];
-  BLI_path_join(filepath, sizeof(filepath), user_config_dir, BLENDER_RECENT_SEARCHES_FILE);
+  BLI_path_join(
+      filepath, sizeof(filepath), user_config_dir->c_str(), BLENDER_RECENT_SEARCHES_FILE);
   return std::string(filepath);
 }
 
diff --git a/source/blender/editors/render/render_preview.cc b/source/blender/editors/render/render_preview.cc
index 3c49a45e2f4..760f653d013 100644
--- a/source/blender/editors/render/render_preview.cc
+++ b/source/blender/editors/render/render_preview.cc
@@ -1332,10 +1332,11 @@ static ImBuf *icon_preview_imbuf_from_brush(Brush *brush)
 
     /* Otherwise lets try to find it in other directories. */
     if (!(brush->icon_imbuf)) {
-      const char *brushicons_dir = BKE_appdir_folder_id(BLENDER_DATAFILES, "brushicons");
+      const std::optional<std::string> brushicons_dir = BKE_appdir_folder_id(BLENDER_DATAFILES,
+                                                                             "brushicons");
       /* Expected to be found, but don't crash if it's not. */
-      if (brushicons_dir) {
-        BLI_path_join(filepath, sizeof(filepath), brushicons_dir, brush->icon_filepath);
+      if (brushicons_dir.has_value()) {
+        BLI_path_join(filepath, sizeof(filepath), brushicons_dir->c_str(), brush->icon_filepath);
 
         /* Use default color spaces. */
         brush->icon_imbuf = IMB_loadiffname(filepath, flags, nullptr);
diff --git a/source/blender/editors/screen/workspace_edit.cc b/source/blender/editors/screen/workspace_edit.cc
index 8b789260cac..c73b8f90e56 100644
--- a/source/blender/editors/screen/workspace_edit.cc
+++ b/source/blender/editors/screen/workspace_edit.cc
@@ -405,11 +405,13 @@ static void WORKSPACE_OT_append_activate(wmOperatorType *ot)
 
 static WorkspaceConfigFileData *workspace_config_file_read(const char *app_template)
 {
-  const char *cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, app_template);
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG,
+                                                                 app_template);
   char startup_file_path[FILE_MAX] = {0};
 
-  if (cfgdir) {
-    BLI_path_join(startup_file_path, sizeof(startup_file_path), cfgdir, BLENDER_STARTUP_FILE);
+  if (cfgdir.has_value()) {
+    BLI_path_join(
+        startup_file_path, sizeof(startup_file_path), cfgdir->c_str(), BLENDER_STARTUP_FILE);
   }
 
   bool has_path = BLI_exists(startup_file_path);
diff --git a/source/blender/editors/space_file/file_ops.cc b/source/blender/editors/space_file/file_ops.cc
index 80fb292f8f7..589fabec3fd 100644
--- a/source/blender/editors/space_file/file_ops.cc
+++ b/source/blender/editors/space_file/file_ops.cc
@@ -382,15 +382,16 @@ static bool fsmenu_write_file_and_refresh_or_report_error(FSMenu *fsmenu,
 {
   /* NOTE: use warning instead of error here, because the bookmark operation may be part of
    * other actions which should not cause the operator to fail entirely. */
-  const char *cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr);
-  if (UNLIKELY(!cfgdir)) {
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG,
+                                                                        nullptr);
+  if (!cfgdir.has_value()) {
     BKE_report(reports, RPT_ERROR, "Unable to create configuration directory to write bookmarks");
     return false;
   }
 
   char filepath[FILE_MAX];
-  BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_BOOKMARK_FILE);
-  if (UNLIKELY(!fsmenu_write_file(fsmenu, filepath))) {
+  BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_BOOKMARK_FILE);
+  if (!fsmenu_write_file(fsmenu, filepath)) {
     BKE_reportf(reports, RPT_ERROR, "Unable to open or write bookmark file \"%s\"", filepath);
     return false;
   }
diff --git a/source/blender/editors/space_file/fsmenu.cc b/source/blender/editors/space_file/fsmenu.cc
index 1d1c324d466..2d70206177e 100644
--- a/source/blender/editors/space_file/fsmenu.cc
+++ b/source/blender/editors/space_file/fsmenu.cc
@@ -136,11 +136,13 @@ void ED_fsmenu_entry_set_path(FSMenuEntry *fsentry, const char *path)
 
     fsentry->path = (path && path[0]) ? BLI_strdup(path) : nullptr;
 
-    BLI_path_join(tmp_name,
-                  sizeof(tmp_name),
-                  BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr),
-                  BLENDER_BOOKMARK_FILE);
-    fsmenu_write_file(ED_fsmenu_get(), tmp_name);
+    const std::optional<std::string> user_config_dir = BKE_appdir_folder_id_create(
+        BLENDER_USER_CONFIG, nullptr);
+
+    if (user_config_dir.has_value()) {
+      BLI_path_join(tmp_name, sizeof(tmp_name), user_config_dir->c_str(), BLENDER_BOOKMARK_FILE);
+      fsmenu_write_file(ED_fsmenu_get(), tmp_name);
+    }
   }
 }
 
@@ -200,11 +202,13 @@ void ED_fsmenu_entry_set_name(FSMenuEntry *fsentry, const char *name)
       STRNCPY(fsentry->name, name);
     }
 
-    BLI_path_join(tmp_name,
-                  sizeof(tmp_name),
-                  BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr),
-                  BLENDER_BOOKMARK_FILE);
-    fsmenu_write_file(ED_fsmenu_get(), tmp_name);
+    const std::optional<std::string> user_config_dir = BKE_appdir_folder_id_create(
+        BLENDER_USER_CONFIG, nullptr);
+
+    if (user_config_dir.has_value()) {
+      BLI_path_join(tmp_name, sizeof(tmp_name), user_config_dir->c_str(), BLENDER_BOOKMARK_FILE);
+      fsmenu_write_file(ED_fsmenu_get(), tmp_name);
+    }
   }
 }
 
diff --git a/source/blender/editors/space_file/space_file.cc b/source/blender/editors/space_file/space_file.cc
index 3234efae175..03463b0d40a 100644
--- a/source/blender/editors/space_file/space_file.cc
+++ b/source/blender/editors/space_file/space_file.cc
@@ -1023,15 +1023,15 @@ void ED_file_exit()
 
 void ED_file_read_bookmarks()
 {
-  const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
 
   fsmenu_free();
 
   fsmenu_read_system(ED_fsmenu_get(), true);
 
-  if (cfgdir) {
+  if (cfgdir.has_value()) {
     char filepath[FILE_MAX];
-    BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_BOOKMARK_FILE);
+    BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_BOOKMARK_FILE);
     fsmenu_read_bookmarks(ED_fsmenu_get(), filepath);
   }
 }
diff --git a/source/blender/freestyle/intern/application/AppConfig.cpp b/source/blender/freestyle/intern/application/AppConfig.cpp
index b198ba48aa9..42699a1f607 100644
--- a/source/blender/freestyle/intern/application/AppConfig.cpp
+++ b/source/blender/freestyle/intern/application/AppConfig.cpp
@@ -23,7 +23,8 @@ Path::Path()
 {
   // get the root directory
   // soc
-  setRootDir(BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, nullptr));
+  const std::optional<std::string> path = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, nullptr);
+  setRootDir(path.value_or(BKE_appdir_program_dir()));
 
   _pInstance = this;
 }
diff --git a/source/blender/freestyle/intern/python/BPy_Freestyle.cpp b/source/blender/freestyle/intern/python/BPy_Freestyle.cpp
index 4f8c51acf97..fc5de0e7cce 100644
--- a/source/blender/freestyle/intern/python/BPy_Freestyle.cpp
+++ b/source/blender/freestyle/intern/python/BPy_Freestyle.cpp
@@ -540,10 +540,11 @@ PyObject *Freestyle_Init()
   PyDict_SetItemString(PySys_GetObject("modules"), module_definition.m_name, module);
 
   // update 'sys.path' for Freestyle Python API modules
-  const char *const path = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, "freestyle");
-  if (path) {
+  const std::optional<std::string> path = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS,
+                                                               "freestyle");
+  if (path.has_value()) {
     char modpath[FILE_MAX];
-    BLI_path_join(modpath, sizeof(modpath), path, "modules");
+    BLI_path_join(modpath, sizeof(modpath), path->c_str(), "modules");
     PyObject *sys_path = PySys_GetObject("path"); /* borrow */
     PyObject *py_modpath = PyC_UnicodeFromBytes(modpath);
     PyList_Append(sys_path, py_modpath);
diff --git a/source/blender/imbuf/intern/colormanagement.cc b/source/blender/imbuf/intern/colormanagement.cc
index 08c326700a5..ee8e94ddae6 100644
--- a/source/blender/imbuf/intern/colormanagement.cc
+++ b/source/blender/imbuf/intern/colormanagement.cc
@@ -653,7 +653,6 @@ static void colormanage_free_config()
 void colormanagement_init()
 {
   const char *ocio_env;
-  const char *configdir;
   char configfile[FILE_MAX];
   OCIO_ConstConfigRcPtr *config = nullptr;
 
@@ -669,10 +668,11 @@ void colormanagement_init()
   }
 
   if (config == nullptr) {
-    configdir = BKE_appdir_folder_id(BLENDER_DATAFILES, "colormanagement");
+    const std::optional<std::string> configdir = BKE_appdir_folder_id(BLENDER_DATAFILES,
+                                                                      "colormanagement");
 
-    if (configdir) {
-      BLI_path_join(configfile, sizeof(configfile), configdir, BCM_CONFIG_FILE);
+    if (configdir.has_value()) {
+      BLI_path_join(configfile, sizeof(configfile), configdir->c_str(), BCM_CONFIG_FILE);
 
       config = OCIO_configCreateFromFile(configfile);
     }
diff --git a/source/blender/python/intern/bpy.cc b/source/blender/python/intern/bpy.cc
index 8e8c4679421..650f6d5c55d 100644
--- a/source/blender/python/intern/bpy.cc
+++ b/source/blender/python/intern/bpy.cc
@@ -74,14 +74,13 @@ static PyObject *bpy_script_paths(PyObject * /*self*/)
 {
   PyObject *ret = PyTuple_New(2);
   PyObject *item;
-  const char *path;
 
-  path = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, nullptr);
-  item = PyC_UnicodeFromBytes(path ? path : "");
+  std::optional<std::string> path = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, nullptr);
+  item = PyC_UnicodeFromBytes(path.has_value() ? path->c_str() : "");
   BLI_assert(item != nullptr);
   PyTuple_SET_ITEM(ret, 0, item);
   path = BKE_appdir_folder_id(BLENDER_USER_SCRIPTS, nullptr);
-  item = PyC_UnicodeFromBytes(path ? path : "");
+  item = PyC_UnicodeFromBytes(path.has_value() ? path->c_str() : "");
   BLI_assert(item != nullptr);
   PyTuple_SET_ITEM(ret, 1, item);
 
@@ -249,10 +248,11 @@ static PyObject *bpy_user_resource(PyObject * /*self*/, PyObject *args, PyObject
 
   /* same logic as BKE_appdir_folder_id_create(),
    * but best leave it up to the script author to create */
-  const char *path = BKE_appdir_folder_id_user_notest(type.value_found, subdir_data.value);
+  const std::optional<std::string> path = BKE_appdir_folder_id_user_notest(type.value_found,
+                                                                           subdir_data.value);
   Py_XDECREF(subdir_data.value_coerce);
 
-  return PyC_UnicodeFromBytes(path ? path : "");
+  return PyC_UnicodeFromBytes(path.has_value() ? path->c_str() : "");
 }
 
 PyDoc_STRVAR(bpy_system_resource_doc,
@@ -297,10 +297,10 @@ static PyObject *bpy_system_resource(PyObject * /*self*/, PyObject *args, PyObje
     return nullptr;
   }
 
-  const char *path = BKE_appdir_folder_id(type.value_found, subdir_data.value);
+  std::optional<std::string> path = BKE_appdir_folder_id(type.value_found, subdir_data.value);
   Py_XDECREF(subdir_data.value_coerce);
 
-  return PyC_UnicodeFromBytes(path ? path : "");
+  return PyC_UnicodeFromBytes(path.has_value() ? path->c_str() : "");
 }
 
 PyDoc_STRVAR(
@@ -328,7 +328,6 @@ static PyObject *bpy_resource_path(PyObject * /*self*/, PyObject *args, PyObject
   PyC_StringEnum type = {type_items};
 
   int major = BLENDER_VERSION / 100, minor = BLENDER_VERSION % 100;
-  const char *path;
 
   static const char *_keywords[] = {"type", "major", "minor", nullptr};
   static _PyArg_Parser _parser = {
@@ -347,9 +346,10 @@ static PyObject *bpy_resource_path(PyObject * /*self*/, PyObject *args, PyObject
     return nullptr;
   }
 
-  path = BKE_appdir_resource_path_id_with_version(type.value_found, false, (major * 100) + minor);
+  const std::optional<std::string> path = BKE_appdir_resource_path_id_with_version(
+      type.value_found, false, (major * 100) + minor);
 
-  return PyC_UnicodeFromBytes(path ? path : "");
+  return PyC_UnicodeFromBytes(path.has_value() ? path->c_str() : "");
 }
 
 /* This is only exposed for tests, see: `tests/python/bl_pyapi_bpy_driver_secure_eval.py`. */
@@ -643,11 +643,12 @@ void BPy_init_modules(bContext *C)
   PyObject *mod;
 
   /* Needs to be first since this dir is needed for future modules */
-  const char *const modpath = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS, "modules");
-  if (modpath) {
+  const std::optional<std::string> modpath = BKE_appdir_folder_id(BLENDER_SYSTEM_SCRIPTS,
+                                                                  "modules");
+  if (modpath.has_value()) {
     // printf("bpy: found module path '%s'.\n", modpath);
     PyObject *sys_path = PySys_GetObject("path"); /* borrow */
-    PyObject *py_modpath = PyC_UnicodeFromBytes(modpath);
+    PyObject *py_modpath = PyC_UnicodeFromBytes(modpath->c_str());
     PyList_Insert(sys_path, 0, py_modpath); /* add first */
     Py_DECREF(py_modpath);
   }
diff --git a/source/blender/python/intern/bpy_interface.cc b/source/blender/python/intern/bpy_interface.cc
index 9d6ee0cafdd..58e24bf588d 100644
--- a/source/blender/python/intern/bpy_interface.cc
+++ b/source/blender/python/intern/bpy_interface.cc
@@ -434,21 +434,22 @@ void BPY_python_start(bContext *C, int argc, const char **argv)
 
     /* Allow to use our own included Python. `py_path_bundle` may be nullptr. */
     {
-      const char *py_path_bundle = BKE_appdir_folder_id(BLENDER_SYSTEM_PYTHON, nullptr);
-      if (py_path_bundle != nullptr) {
+      const std::optional<std::string> py_path_bundle = BKE_appdir_folder_id(BLENDER_SYSTEM_PYTHON,
+                                                                             nullptr);
+      if (py_path_bundle.has_value()) {
 
 #  ifdef __APPLE__
         /* Mac-OS allows file/directory names to contain `:` character
          * (represented as `/` in the Finder) but current Python lib (as of release 3.1.1)
          * doesn't handle these correctly. */
-        if (strchr(py_path_bundle, ':')) {
+        if (strchr(py_path_bundle->c_str(), ':')) {
           fprintf(stderr,
                   "Warning! Blender application is located in a path containing ':' or '/' chars\n"
                   "This may make Python import function fail\n");
         }
 #  endif /* __APPLE__ */
 
-        status = PyConfig_SetBytesString(&config, &config.home, py_path_bundle);
+        status = PyConfig_SetBytesString(&config, &config.home, py_path_bundle->c_str());
         pystatus_exit_on_error(status);
 
 #  ifdef PYTHON_SSL_CERT_FILE
@@ -458,7 +459,7 @@ void BPY_python_start(bContext *C, int argc, const char **argv)
           const char *ssl_cert_file_suffix = PYTHON_SSL_CERT_FILE;
           char ssl_cert_file[FILE_MAX];
           BLI_path_join(
-              ssl_cert_file, sizeof(ssl_cert_file), py_path_bundle, ssl_cert_file_suffix);
+              ssl_cert_file, sizeof(ssl_cert_file), py_path_bundle->c_str(), ssl_cert_file_suffix);
           BLI_setenv(ssl_cert_file_env, ssl_cert_file);
         }
 #  endif /* PYTHON_SSL_CERT_FILE */
diff --git a/source/blender/windowmanager/intern/wm_files.cc b/source/blender/windowmanager/intern/wm_files.cc
index 4fda75b58a2..e21c6d043c6 100644
--- a/source/blender/windowmanager/intern/wm_files.cc
+++ b/source/blender/windowmanager/intern/wm_files.cc
@@ -1279,13 +1279,15 @@ void wm_homefile_read_ex(bContext *C,
   app_template_system[0] = '\0';
   app_template_config[0] = '\0';
 
-  const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
   if (!use_factory_settings) {
-    if (cfgdir) {
-      BLI_path_join(filepath_startup, sizeof(filepath_startup), cfgdir, BLENDER_STARTUP_FILE);
+    if (cfgdir.has_value()) {
+      BLI_path_join(
+          filepath_startup, sizeof(filepath_startup), cfgdir->c_str(), BLENDER_STARTUP_FILE);
       filepath_startup_is_factory = false;
       if (use_userdef) {
-        BLI_path_join(filepath_userdef, sizeof(filepath_startup), cfgdir, BLENDER_USERPREF_FILE);
+        BLI_path_join(
+            filepath_userdef, sizeof(filepath_startup), cfgdir->c_str(), BLENDER_USERPREF_FILE);
       }
     }
     else {
@@ -1328,8 +1330,9 @@ void wm_homefile_read_ex(bContext *C,
 
     /* note that the path is being set even when 'use_factory_settings == true'
      * this is done so we can load a templates factory-settings */
-    if (!use_factory_settings) {
-      BLI_path_join(app_template_config, sizeof(app_template_config), cfgdir, app_template);
+    if (!use_factory_settings && cfgdir.has_value()) {
+      BLI_path_join(
+          app_template_config, sizeof(app_template_config), cfgdir->c_str(), app_template);
       BLI_path_join(
           filepath_startup, sizeof(filepath_startup), app_template_config, BLENDER_STARTUP_FILE);
       filepath_startup_is_factory = false;
@@ -1534,8 +1537,8 @@ void wm_homefile_read_post(bContext *C, const wmFileReadPost_Params *params_file
 
 void wm_history_file_read()
 {
-  const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
-  if (!cfgdir) {
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+  if (!cfgdir.has_value()) {
     return;
   }
 
@@ -1543,7 +1546,7 @@ void wm_history_file_read()
   LinkNode *l;
   int num;
 
-  BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_HISTORY_FILE);
+  BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_HISTORY_FILE);
 
   LinkNode *lines = BLI_file_read_as_lines(filepath);
 
@@ -1597,17 +1600,17 @@ static RecentFile *wm_file_history_find(const char *filepath)
  */
 static void wm_history_file_write()
 {
-  const char *user_config_dir;
   char filepath[FILE_MAX];
   FILE *fp;
 
   /* will be nullptr in background mode */
-  user_config_dir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, nullptr);
-  if (!user_config_dir) {
+  const std::optional<std::string> user_config_dir = BKE_appdir_folder_id_create(
+      BLENDER_USER_CONFIG, nullptr);
+  if (!user_config_dir.has_value()) {
     return;
   }
 
-  BLI_path_join(filepath, sizeof(filepath), user_config_dir, BLENDER_HISTORY_FILE);
+  BLI_path_join(filepath, sizeof(filepath), user_config_dir->c_str(), BLENDER_HISTORY_FILE);
 
   fp = BLI_fopen(filepath, "w");
   if (fp) {
@@ -2093,10 +2096,11 @@ static void wm_autosave_location(char filepath[FILE_MAX])
    * If this is still the case on WIN32 - other features such as copy-paste will also fail.
    * We could support #BLENDER_USER_AUTOSAVE on all platforms or remove it entirely. */
 #ifdef WIN32
+  std::optional<std::string> savedir;
   if (!BLI_exists(tempdir_base)) {
-    const char *savedir = BKE_appdir_folder_id_create(BLENDER_USER_AUTOSAVE, nullptr);
-    if (savedir) {
-      tempdir_base = savedir;
+    savedir = BKE_appdir_folder_id_create(BLENDER_USER_AUTOSAVE, nullptr);
+    if (savedir.has_value()) {
+      tempdir_base = savedir->c_str();
     }
   }
 #endif
@@ -2277,8 +2281,9 @@ static int wm_homefile_write_exec(bContext *C, wmOperator *op)
   int fileflags;
 
   const char *app_template = U.app_template[0] ? U.app_template : nullptr;
-  const char *const cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG, app_template);
-  if (cfgdir == nullptr) {
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id_create(BLENDER_USER_CONFIG,
+                                                                        app_template);
+  if (!cfgdir.has_value()) {
     BKE_report(op->reports, RPT_ERROR, "Unable to create user config path");
     return OPERATOR_CANCELLED;
   }
@@ -2296,7 +2301,7 @@ static int wm_homefile_write_exec(bContext *C, wmOperator *op)
   /* update keymaps in user preferences */
   WM_keyconfig_update(wm);
 
-  BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_STARTUP_FILE);
+  BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_STARTUP_FILE);
 
   printf("Writing homefile: \"%s\" ", filepath);
 
diff --git a/source/blender/windowmanager/intern/wm_init_exit.cc b/source/blender/windowmanager/intern/wm_init_exit.cc
index 2a1df9eef93..8f8f3162fc7 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.cc
+++ b/source/blender/windowmanager/intern/wm_init_exit.cc
@@ -375,10 +375,10 @@ static bool wm_init_splash_show_on_startup_check()
   else {
     /* A less common case, if there is no user preferences, show the splash screen
      * so the user has the opportunity to restore settings from a previous version. */
-    const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
-    if (cfgdir) {
+    const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+    if (cfgdir.has_value()) {
       char userpref[FILE_MAX];
-      BLI_path_join(userpref, sizeof(userpref), cfgdir, BLENDER_USERPREF_FILE);
+      BLI_path_join(userpref, sizeof(userpref), cfgdir->c_str(), BLENDER_USERPREF_FILE);
       if (!BLI_exists(userpref)) {
         use_splash = true;
       }
diff --git a/source/blender/windowmanager/intern/wm_platform_support.cc b/source/blender/windowmanager/intern/wm_platform_support.cc
index ecd7e103ca0..fd49aa21481 100644
--- a/source/blender/windowmanager/intern/wm_platform_support.cc
+++ b/source/blender/windowmanager/intern/wm_platform_support.cc
@@ -36,14 +36,14 @@ static bool wm_platform_support_check_approval(const char *platform_support_key,
   if (G.factory_startup) {
     return false;
   }
-  const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
-  if (!cfgdir) {
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+  if (!cfgdir.has_value()) {
     return false;
   }
 
   bool result = false;
   char filepath[FILE_MAX];
-  BLI_path_join(filepath, sizeof(filepath), cfgdir, BLENDER_PLATFORM_SUPPORT_FILE);
+  BLI_path_join(filepath, sizeof(filepath), cfgdir->c_str(), BLENDER_PLATFORM_SUPPORT_FILE);
   LinkNode *lines = BLI_file_read_as_lines(filepath);
   for (LinkNode *line_node = lines; line_node; line_node = line_node->next) {
     const char *line = static_cast<char *>(line_node->link);
diff --git a/source/blender/windowmanager/intern/wm_splash_screen.cc b/source/blender/windowmanager/intern/wm_splash_screen.cc
index 6958544c74d..8e396f5d2f1 100644
--- a/source/blender/windowmanager/intern/wm_splash_screen.cc
+++ b/source/blender/windowmanager/intern/wm_splash_screen.cc
@@ -216,10 +216,10 @@ static uiBlock *wm_block_create_splash(bContext *C, ARegion *region, void * /*ar
 
   MenuType *mt;
   char userpref[FILE_MAX];
-  const char *const cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
+  const std::optional<std::string> cfgdir = BKE_appdir_folder_id(BLENDER_USER_CONFIG, nullptr);
 
-  if (cfgdir) {
-    BLI_path_join(userpref, sizeof(userpref), cfgdir, BLENDER_USERPREF_FILE);
+  if (cfgdir.has_value()) {
+    BLI_path_join(userpref, sizeof(userpref), cfgdir->c_str(), BLENDER_USERPREF_FILE);
   }
 
   /* Draw setup screen if no preferences have been saved yet. */