When the File Output node exits early in convertToOperations (in case not rendering), it should still unlink all inputs to avoid debug assert failure that checks for remaining Node connections (debug_check_node_connections).

source/blender/compositor/nodes/COM_OutputFileNode.cpp

@@ -41,6 +41,12 @@ void OutputFileNode::convertToOperations(ExecutionSystem *graph, CompositorConte
 		 * otherwise, it overwrites the output files just
 		 * scrubbing through the timeline when the compositor updates.
 		 */
+		
+		/* still, need to unlink input sockets to remove the node from the graph completely */
+		int num_inputs = getNumberOfInputSockets();
+		for (int i = 0; i < num_inputs; ++i) {
+			getInputSocket(i)->unlinkConnections(graph);
+		}
 		return;
 	}