Quick answer: Unity asset postprocessor triggering imports of other assets causing import order deadlock? Postprocessors can't request imports - defer to delayCall.

Postprocessor that imports auxiliary files freezes editor at import.

Defer to delayCall

EditorApplication.delayCall += () => {{
  AssetDatabase.ImportAsset(path);
}};

Runs after the current import pipeline.

Or use a deferred queue

Postprocessor appends to a static List; EditorWindow processes. Structured.

Avoid recursive imports

If A imports B which imports A, deadlock. Architecture issue; restructure.

“Asset Database is reentrant-hostile. Imports inside imports deadlock.”

Document the postprocessor pattern. New contributors will write recursive imports otherwise.

Related reading