diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 1fc2da08bc6..e7bcfa8226d 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1210,7 +1210,7 @@ class CYCLES_CAMERA_PT_lens_custom_parameters(CyclesButtonsPanel, Panel):
 
         col = layout.column()
         for key in ccam.keys():
-            col.prop(ccam, f'["{key}"]')
+            col.prop(ccam, f'["{key}"]', text=bpy.path.display_name(key))
 
 
 class CYCLES_PT_context_material(CyclesButtonsPanel, Panel):
diff --git a/intern/cycles/kernel/util/ies.h b/intern/cycles/kernel/util/ies.h
index ee09e526162..8642082c0a3 100644
--- a/intern/cycles/kernel/util/ies.h
+++ b/intern/cycles/kernel/util/ies.h
@@ -27,22 +27,29 @@ ccl_device_inline float interpolate_ies_vertical(KernelGlobals kg,
    * we can just take the corresponding value at the current horizontal coordinate. */
 
 #define IES_LOOKUP(v) kernel_data_fetch(ies, ofs + h * v_num + (v))
-  float a = 0.0f;
+
+  /* Look up the inner two points directly. */
+  const float c = IES_LOOKUP(v + 1);
+  const float b = IES_LOOKUP(v);
+
+  /* Look up first point, or fall back to second point if not available. */
+  float a = b;
   if (v > 0) {
     a = IES_LOOKUP(v - 1);
   }
   else if (wrap_vlow) {
     a = IES_LOOKUP(1);
   }
-  const float b = IES_LOOKUP(v);
-  const float c = IES_LOOKUP(v + 1);
-  float d = 0.0f;
+
+  /* Look up last point, or fall back to third point if not available. */
+  float d = c;
   if (v + 2 < v_num) {
     d = IES_LOOKUP(v + 2);
   }
   else if (wrap_vhigh) {
     d = IES_LOOKUP(v_num - 2);
   }
+
 #undef IES_LOOKUP
 
   return cubic_interp(a, b, c, d, v_frac);
@@ -105,7 +112,14 @@ ccl_device_inline float kernel_ies_interp(KernelGlobals kg,
   /* Skip forward to the actual intensity data. */
   ofs += h_num + v_num;
 
-  float a = 0.0f;
+  /* Interpolate the inner two points directly. */
+  const float b = interpolate_ies_vertical(
+      kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i);
+  const float c = interpolate_ies_vertical(
+      kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i + 1);
+
+  /* Interpolate first point, or fall back to second point if not available. */
+  float a = b;
   if (h_i > 0) {
     a = interpolate_ies_vertical(kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i - 1);
   }
@@ -113,11 +127,9 @@ ccl_device_inline float kernel_ies_interp(KernelGlobals kg,
     /* The last entry (360°) equals the first one, so we need to wrap around to the one before. */
     a = interpolate_ies_vertical(kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_num - 2);
   }
-  const float b = interpolate_ies_vertical(
-      kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i);
-  const float c = interpolate_ies_vertical(
-      kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i + 1);
-  float d = 0.0f;
+
+  /* Interpolate last point, or fall back to second point if not available. */
+  float d = b;
   if (h_i + 2 < h_num) {
     d = interpolate_ies_vertical(kg, ofs, wrap_vlow, wrap_vhigh, v_i, v_num, v_frac, h_i + 2);
   }
diff --git a/scripts/templates_osl/advanced_camera.osl b/scripts/templates_osl/advanced_camera.osl
index 1997886177b..124f4d1f82b 100644
--- a/scripts/templates_osl/advanced_camera.osl
+++ b/scripts/templates_osl/advanced_camera.osl
@@ -37,7 +37,7 @@ shader camera(float focal_length = 50.0 [[ float min = 0.0,
               float distortion_k3 = 0.0,
               float swirl_scale = 100.0,
               float swirl_amplitude = 0.01,
-              float swirl_W = 0.0 [[ float sensitivity = 1]],
+              float swirl_w = 0.0 [[ float sensitivity = 1]],
               output point position = 0.0,
               output vector direction = 0.0,
               output color throughput = 1.0)
@@ -61,7 +61,7 @@ shader camera(float focal_length = 50.0 [[ float min = 0.0,
   Pcam = Pcam * sensor_size / focal_length;
 
   if (do_swirl) {
-    Pcam += swirl_amplitude * noise("perlin", Pcam * swirl_scale, swirl_W);
+    Pcam += swirl_amplitude * noise("perlin", Pcam * swirl_scale, swirl_w);
   }
 
   direction = normalize(vector(Pcam.x, Pcam.y, 1.0));
diff --git a/source/blender/asset_system/AS_asset_catalog.hh b/source/blender/asset_system/AS_asset_catalog.hh
index a82b86351d0..364bebfc3f6 100644
--- a/source/blender/asset_system/AS_asset_catalog.hh
+++ b/source/blender/asset_system/AS_asset_catalog.hh
@@ -71,7 +71,7 @@ class AssetCatalogService {
    *
    * This "dirty" state is tracked per catalog, so that it's possible to gracefully load changes
    * from disk. Any catalog with unsaved changes will not be overwritten by on-disk changes. */
-  void tag_has_unsaved_changes(AssetCatalog *edited_catalog);
+  void tag_has_unsaved_changes(AssetCatalog *edited_catalog = nullptr);
   bool has_unsaved_changes() const;
 
   /**
@@ -159,8 +159,15 @@ class AssetCatalogService {
    */
   AssetCatalogFilter create_catalog_filter(CatalogID active_catalog_id) const;
 
-  /** Create a catalog with some sensible auto-generated catalog ID.
-   * The catalog will be saved to the default catalog file. */
+  /**
+   * Create a catalog with some sensible auto-generated catalog ID.
+   * The catalog will be saved to the default catalog file.
+   *
+   * NOTE: this does NOT mark the catalog service itself as 'has changes'. The caller is
+   * responsible for that.
+   *
+   * \see #tag_has_unsaved_changes()
+   */
   AssetCatalog *create_catalog(const AssetCatalogPath &catalog_path);
 
   /**
@@ -228,6 +235,11 @@ class AssetCatalogService {
    * will be removed from a CDF when saved to disk.
    *
    * This is a lower-level function than #prune_catalogs_by_path.
+   *
+   * NOTE: this does NOT mark the catalog service itself as 'has changes'. The caller is
+   * responsible for that.
+   *
+   * \see #tag_has_unsaved_changes()
    */
   void delete_catalog_by_id_soft(CatalogID catalog_id);
 
diff --git a/source/blender/asset_system/intern/asset_catalog.cc b/source/blender/asset_system/intern/asset_catalog.cc
index 21efd40f20a..02ce2d581db 100644
--- a/source/blender/asset_system/intern/asset_catalog.cc
+++ b/source/blender/asset_system/intern/asset_catalog.cc
@@ -482,9 +482,19 @@ bool AssetCatalogService::write_to_disk_ex(const CatalogFilePath &blend_file_pat
 {
   /* TODO(Sybren): expand to support multiple CDFs. */
 
-  /* - Already loaded a CDF from disk? -> Always write to that file. */
+  /* - Already loaded a CDF from disk? -> Only write to that file when there were actual changes.
+   * This prevents touching the file, which can cause issues when multiple Blender instances are
+   * accessing the same file (like on shared storage, Syncthing, etc.). See #111576.
+   */
   if (catalog_collection_->catalog_definition_file_) {
+    /* Always sync with what's on disk. */
     this->reload_catalogs();
+
+    if (!this->has_unsaved_changes() &&
+        catalog_collection_->catalog_definition_file_->exists_on_disk())
+    {
+      return true;
+    }
     return catalog_collection_->catalog_definition_file_->write_to_disk();
   }
 
diff --git a/source/blender/asset_system/intern/asset_catalog_definition_file.cc b/source/blender/asset_system/intern/asset_catalog_definition_file.cc
index 4364b85a75a..5cf9aff7790 100644
--- a/source/blender/asset_system/intern/asset_catalog_definition_file.cc
+++ b/source/blender/asset_system/intern/asset_catalog_definition_file.cc
@@ -185,6 +185,11 @@ bool AssetCatalogDefinitionFile::write_to_disk(const CatalogFilePath &dest_file_
   return true;
 }
 
+bool AssetCatalogDefinitionFile::exists_on_disk() const
+{
+  return BLI_exists(this->file_path.c_str());
+}
+
 bool AssetCatalogDefinitionFile::write_to_disk_unsafe(const CatalogFilePath &dest_file_path) const
 {
   char directory[PATH_MAX];
diff --git a/source/blender/asset_system/intern/asset_catalog_definition_file.hh b/source/blender/asset_system/intern/asset_catalog_definition_file.hh
index c7d99c9677a..870a20b64ba 100644
--- a/source/blender/asset_system/intern/asset_catalog_definition_file.hh
+++ b/source/blender/asset_system/intern/asset_catalog_definition_file.hh
@@ -55,6 +55,11 @@ class AssetCatalogDefinitionFile {
    */
   bool write_to_disk(const CatalogFilePath &dest_file_path) const;
 
+  /**
+   * Returns whether this file exists on disk.
+   */
+  bool exists_on_disk() const;
+
   bool contains(CatalogID catalog_id) const;
   /** Add a catalog, overwriting the one with the same catalog ID. */
   void add_overwrite(AssetCatalog *catalog);
diff --git a/source/blender/asset_system/tests/asset_catalog_test.cc b/source/blender/asset_system/tests/asset_catalog_test.cc
index 0334a203318..cbb4fb8c328 100644
--- a/source/blender/asset_system/tests/asset_catalog_test.cc
+++ b/source/blender/asset_system/tests/asset_catalog_test.cc
@@ -341,6 +341,7 @@ TEST_F(AssetCatalogTest, on_blendfile_save__with_existing_cdf)
   TestableAssetCatalogService service(cdf_filename);
   service.load_from_disk();
   const AssetCatalog *cat = service.create_catalog("some/catalog/path");
+  service.tag_has_unsaved_changes();
 
   const CatalogFilePath blendfilename = top_level_dir + "subdir" + SEP_STR + "some_file.blend";
   ASSERT_TRUE(service.write_to_disk(blendfilename));
@@ -458,6 +459,10 @@ TEST_F(AssetCatalogTest, create_first_catalog_from_scratch)
   /* Creating a new catalog should not save anything to disk yet. */
   EXPECT_FALSE(BLI_exists(temp_lib_root.c_str()));
 
+  /* Creating a new catalog should not mark the asset service as 'dirty'; that's
+   * the caller's responsibility. */
+  EXPECT_FALSE(service.has_unsaved_changes());
+
   /* Writing to disk should create the directory + the default file. */
   service.write_to_disk(temp_lib_root + "phony.blend");
   EXPECT_TRUE(BLI_is_dir(temp_lib_root.c_str()));
@@ -498,6 +503,7 @@ TEST_F(AssetCatalogTest, create_catalog_after_loading_file)
   /* This should create a new catalog but not write to disk. */
   const AssetCatalog *new_catalog = service.create_catalog("new/catalog");
   const bUUID new_catalog_id = new_catalog->catalog_id;
+  service.tag_has_unsaved_changes();
 
   /* Reload the on-disk catalog file. */
   TestableAssetCatalogService loaded_service(temp_lib_root);
@@ -887,6 +893,7 @@ TEST_F(AssetCatalogTest, backups)
   TestableAssetCatalogService service(cdf_dir);
   service.load_from_disk();
   service.delete_catalog_by_id_soft(UUID_POSES_ELLIE);
+  service.tag_has_unsaved_changes();
   service.write_to_disk(cdf_dir + "phony.blend");
 
   const CatalogFilePath backup_path = writable_cdf_file + "~";
diff --git a/source/blender/blenlib/intern/BLI_mmap.cc b/source/blender/blenlib/intern/BLI_mmap.cc
index d69c4637468..9fc4c747a36 100644
--- a/source/blender/blenlib/intern/BLI_mmap.cc
+++ b/source/blender/blenlib/intern/BLI_mmap.cc
@@ -275,7 +275,9 @@ static void print_error(const char *message)
 {
   char buffer[256];
   size_t length = BLI_string_join(buffer, sizeof(buffer), "BLI_mmap: ", message, "\n");
-  write(STDERR_FILENO, buffer, length);
+  if (write(STDERR_FILENO, buffer, length) < 0) {
+    /* If writing to stderr fails, there is nowhere to write an error about that. */
+  }
 }
 
 static bool try_map_zeros(BLI_mmap_file *file)