Pinecone 403: this project already contains 20 serverless indexes

TL;DR: Each project is capped at 20 serverless indexes. The error message says exactly what to do: delete unused indexes or use a new project. Delete any unused indexes and try again, or create a new project for more serverless indexes.

The fix

TL;DR: Each project is capped at 20 serverless indexes. The error message says exactly what to do: delete unused indexes or use a new project. Delete any unused indexes and try again, or create a new project for more serverless indexes.

The fix

403: the 20-serverless-index project cap

The error

This project already contains 20 serverless indexes, the maximum per project. Delete any unused indexes and try again, or create a new project for more serverless indexes. HTTP 403.

Cause

The project hit its quota. Pinecone caps each project at 20 serverless indexes. The usual way agents get here: one index per experiment, per branch, per tenant, none ever deleted.

Fix

1. List indexes and delete the experiments: pc.list_indexes(), then pc.delete_index(name) for the dead ones. Deletion is permanent; export anything you need first.
2. For multitenancy, stop creating indexes per tenant. One index with one namespace per tenant is the documented pattern, and it also speeds up queries.
3. If you genuinely need more than 20, create a new project.

Trap

Treating this as a bug in the create call and retrying. It is a quota; retries change nothing. The other trap is "temporarily" moving to a second project and now having indexes in two places with no record of which is canonical.

When to use this

• This covers exactly what the title says: Pinecone 403.
• You are setting this up for the first time, or auditing an existing setup.
• You want the key gotchas in one place before you start.

When not to use this

• You are doing a different workflow with Pinecone; these steps are specific to the title above.
• You need the full reference docs; this is the short path, not the manual.

Compatibility

• Not pinned to a specific version; follows current Pinecone behavior.

Pinecone's troubleshooting page for this exact error states the 20-serverless-index per-project limit, gives the full 403 message verbatim, and recommends namespaces for partitioning same-dimension vectors. Verified against live docs 2026-09-26.