n8n-io/n8n · error · NodeOperationError

Error connecting to ChromaDB: ${message}

Error message

Error connecting to ChromaDB: ${message}

What it means

Catch-all NodeOperationError in `getVectorStoreClient` for any failure from `getChromaLibConfig` or `ExtendedChroma.fromExistingCollection`. The original error message is appended. This wraps the LangChain-side Chroma construction that binds the embeddings function, the URL, and the existing collection name into a VectorStore instance.

Source

Thrown at packages/@n8n/nodes-langchain/nodes/vector_store/VectorStoreChromaDB/VectorStoreChromaDB.node.ts:405

	loadFields: retrieveFields,
	insertFields,
	sharedFields,

	async getVectorStoreClient(context, _filter, embeddings, itemIndex) {
		const collection = context.getNodeParameter('chromaCollection', itemIndex, '', {
			extractValue: true,
		});

		if (typeof collection !== 'string') {
			throw new NodeOperationError(context.getNode(), 'Collection must be a string');
		}

		try {
			const config = await getChromaLibConfig(context, collection, itemIndex);
			return await ExtendedChroma.fromExistingCollection(embeddings, config);
		} catch (error) {
			const message = error instanceof Error ? error.message : 'Unknown error';
			throw new NodeOperationError(context.getNode(), `Error connecting to ChromaDB: ${message}`, {
				itemIndex,
			});
		}
	},

	async populateVectorStore(context, embeddings, documents, itemIndex) {
		const collection = context.getNodeParameter('chromaCollection', itemIndex, '', {
			extractValue: true,
		});

		if (typeof collection !== 'string') {
			throw new NodeOperationError(context.getNode(), 'Collection must be a string');
		}

		const options = context.getNodeParameter('options', itemIndex, {});
		const clearCollection = options.clearCollection === true;

		if (clearCollection) {

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Read the appended `message` — it usually says whether the collection is missing or the connection failed.
2. If the collection is missing, create it first (insert mode) or pick an existing one from the dropdown.
3. Verify the credential's URL and API key still match the running ChromaDB.
4. Retry after confirming ChromaDB is reachable from the n8n host.

Example fix

// before
try {
  const config = await getChromaLibConfig(context, collection, itemIndex);
  return await ExtendedChroma.fromExistingCollection(embeddings, config);
} catch (error) {
  const message = error instanceof Error ? error.message : 'Unknown error';
  throw new NodeOperationError(context.getNode(), `Error connecting to ChromaDB: ${message}`, { itemIndex });
}

// after: classify the common 'collection not found' case so the user gets a fix
} catch (error) {
  const message = error instanceof Error ? error.message : 'Unknown error';
  const notFound = /does not exist|not found/i.test(message);
  throw new NodeOperationError(
    context.getNode(),
    `Error connecting to ChromaDB: ${message}`,
    {
      itemIndex,
      description: notFound
        ? `Collection "${collection}" does not exist. Run the node in Insert mode to create it.`
        : 'Verify the ChromaDB URL and credentials.',
    },
  );
}

// Confirm the collection exists before binding it to ExtendedChroma.
async function ensureCollectionExists(client: ChromaClient, name: string): Promise<void> {
  const names = (await client.listCollections()).map((c) => (typeof c === 'string' ? c : c.name));
  if (!names.includes(name)) {
    throw new Error(`Collection "${name}" does not exist; run the node in Insert mode first.`);
  }
}

function isMissingCollectionError(error: unknown): boolean {
  return error instanceof Error && /does not exist|not found/i.test(error.message);
}

try {
  const config = await getChromaLibConfig(context, collection, itemIndex);
  return await ExtendedChroma.fromExistingCollection(embeddings, config);
} catch (error) {
  const message = error instanceof Error ? error.message : 'Unknown error';
  throw new NodeOperationError(context.getNode(), `Error connecting to ChromaDB: ${message}`, {
    itemIndex,
    description: isMissingCollectionError(error)
      ? `Collection "${collection}" does not exist. Run in Insert mode to create it.`
      : 'Verify the ChromaDB URL and credentials.',
  });
}

When it happens

Trigger: The named collection does not exist on the server (so fromExistingCollection cannot bind); the collection exists but has incompatible metadata; the URL/auth config cannot be assembled from the credential; the underlying ChromaClient throws during the first lazy call.

Common situations: User typed a collection name that does not exist yet; collection was deleted between workflow save and run; switching from one credential to another pointing at a different ChromaDB instance; SDK version change altering the fromExistingCollection signature.

Related errors

• Error inserting documents into ChromaDB: ${errorMessage}
• Failed to list ChromaDB collections: ${errorMessage}
• Collection must be a string
• ChromaDB embedding dimension mismatch: ${displayMessage}
• Error: ${error.message}

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/75a5d7a471d04a1c. Report an issue: GitHub.