microsoft/semantic-kernel · error · ServiceInvalidRequestError

Collection with name {collection_name} already exists.

Error message

Collection with name {collection_name} already exists.

What it means

Raised by USearchMemoryStore.create_collection (ServiceInvalidRequestError) when a collection with the given name (after lowercasing) already exists in `self._collections`. The store keys collections by lowercased name, so it treats names case-insensitively and refuses to silently overwrite an existing in-memory index.

Source

Thrown at python/semantic_kernel/connectors/memory_stores/usearch/usearch_memory_store.py:199

            collection_name (str): Name of the collection. Case-insensitive.
                Must have name that is valid file name for the current OS environment.
            ndim (int, optional): Number of dimensions. Defaults to 0.
            metric (Union[str, MetricKind, CompiledMetric], optional): Metric kind. Defaults to MetricKind.IP.
            dtype (Optional[Union[str, ScalarKind]], optional): Data type. Defaults to None.
            connectivity (int, optional): Connectivity parameter. Defaults to None.
            expansion_add (int, optional): Expansion add parameter. Defaults to None.
            expansion_search (int, optional): Expansion search parameter. Defaults to None.
            view (bool, optional): Viewing flag. Defaults to False.

        Raises:
            ValueError: If collection with the given name already exists.
            ValueError: If collection name is empty string.
        """
        collection_name = collection_name.lower()
        if not collection_name:
            raise ServiceInvalidRequestError("Collection name can not be empty.")
        if collection_name in self._collections:
            raise ServiceInvalidRequestError(f"Collection with name {collection_name} already exists.")

        embeddings_index_path = (
            self._get_collection_path(collection_name, file_type=_CollectionFileType.USEARCH)
            if self._persist_directory
            else None
        )

        embeddings_index = Index(
            ndim=ndim,
            metric=metric,
            dtype=dtype,
            connectivity=connectivity,
            expansion_add=expansion_add,
            expansion_search=expansion_search,
            path=embeddings_index_path,
            view=view,
        )

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Check `collection_name.lower() not in store._collections` (or call does_collection_exist) before creating.
2. Delete the existing collection first if you intend to recreate it.
3. If collections are loaded from disk at startup, skip create_collection for names already present.

Example fix

// before
await store.create_collection('docs')
// after
if not await store.does_collection_exist('docs'):
    await store.create_collection('docs')

name = collection_name.lower()
if not await store.does_collection_exist(name):
    await store.create_collection(name)
else:
    logger.info('collection %s already exists; skipping create', name)

from semantic_kernel.exceptions import ServiceInvalidRequestError
try:
    await store.create_collection(name)
except ServiceInvalidRequestError as e:
    if 'already exists' in str(e):
        pass  # idempotent create
    else:
        raise

When it happens

Trigger: Calling `create_collection('Docs')` when 'docs' is already present (loaded from disk at construction, or created earlier in the same process). The name is lowercased before the duplicate check.

Common situations: Re-running an app that re-creates collections on each startup without deleting first; collections auto-loaded from persist_directory that collide with names the app then tries to create; case-variant names ('Docs' vs 'docs') treated as the same.

Related errors

• Collection name can not be empty.
• Path of persist directory is not set
• Expected {expected_storage_files} files for collection {coll
• Collection {collection_name} does not exist, cannot insert.
• Key '{key}' not found in collection '{collection_name}'

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/3e7eac14f3ebb114. Report an issue: GitHub.