AsyncFinalizerInSyncCloseError¶

Symptom

Arrives wrapped inside a FinalizerError (as one entry in .finalizer_errors), naming the type whose cached instance has an async finalizer.

Cause

close_sync() cannot await anything. When it reaches a cached resource whose CacheSettings finalizer is an async function, it can't run it synchronously, so it records this error for that entry instead — and, unlike a normal finalizer failure, keeps the resource's cache entry intact rather than discarding it.

Fix

Use close_async() (or async with container:) for containers that hold any resource with an async finalizer — it's the only path that can actually run that cleanup:

container.resolve(AsyncResource)   # has an async finalizer

try:
    container.close_sync()
except exceptions.FinalizerError as exc:
    # exc.finalizer_errors contains an AsyncFinalizerInSyncCloseError — cache retained, not lost
    ...

await container.close_async()      # recovers: runs the async finalizer, completes cleanup

Prefer async with container: (or await close_async()) by default whenever any provider might have an async finalizer, and treat close_sync() as a fallback only for containers you know are entirely sync.

AsyncFinalizerInSyncCloseError¶

See also¶