supabase mcp unrecognized client_id

TL;DR

An MCP client hitting unrecognized client_id is presenting an OAuth client id Supabase never issued for that project. Work through the checklist: confirm the config file the client actually reads, re-create the integration in the dashboard for a fresh id, paste it exactly, and restart the client fully.

supabase mcp unrecognized client_id

Use this when

• The MCP client fails with unrecognized client_id on every launch
• You followed a setup guide and it never worked
• It broke after dashboard cleanup or project transfer

Not for this skill when

• The MCP server binary wont start at all (thats install/transport)
• The project ref or URL is wrong (thats a different error)
• Auth worked before and now sessions expire (thats refresh, not identity)

Steps

1. Find which config file your client actually reads. IDEs each keep their own:

ls ~/.config/*/mcp.json ~/Library/Application\ Support/*/mcp.json

Expected output: one or more mcp.json paths. Edit the one belonging to the client that fails, not a sibling client's file.

1. Validate the JSON before touching values:

python -m json.tool /path/to/mcp.json

Expected output: the formatted JSON prints with no error. A broken file makes the client ignore the whole Supabase entry, which can surface as identity errors.

1. Re-create the Supabase integration to mint a current client id, then replace the value character-for-character:

Dashboard > Project Settings > Integrations > create the integration again

Expected output: a fresh client id. Ids copied from docs, videos, or old issues were never valid for your project.

1. Restart the client completely and watch the MCP startup log:

# quit the app (not just the window), reopen, check MCP/tool panel

Expected output: Supabase tools listed, no client_id error. MCP config loads once at startup, so restarts are mandatory after edits.

Variant phrasings

unrecognized client_id after project restore

Restored or transferred projects invalidate old integrations. Re-create them; the id doesnt survive the move.

works in one IDE, fails in another

Each IDE has its own mcp.json. The working one has the good id; copy it (or better, create per-client integrations).

Why it happens

Supabase's OAuth registry is per-project and per-integration. Anything that breaks that link (deleted integration, new project, copied doc value, trailing whitespace from a sloppy paste) produces the same message. MCP clients surface it at startup because they validate the connection before listing tools.

Edge cases

• Some clients cache OAuth grants; after fixing the id you may need to clear the client's stored grant to force a fresh flow.
• If two tools share one integration's id and you rotate it, both break; prefer one integration per tool.
• A client id with a trailing newline pasted into JSON is still valid JSON but an invalid id; strip whitespace on paste.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_m7MiCItPna49mqfEPvoz-g