Apify MCP: 401 'User was not found or authentication token is not valid' (apify_api_ prefix)

Check the token starts with apify_api_. Apify API tokens carry a fixed prefix; a token pasted without it (or a truncated copy) fails auth with "User was not found or authentication token is not valid". Re-copy the full token from the Console including the prefix, update the config, restart.

401: User was not found or authentication token is not valid

The fix

1. Open the Apify Console token page and copy the token in full, starting with apify_api_.

Expected: the copied string begins with the prefix.

1. Replace the token value in your MCP config env block.

Expected: the config still parses as valid JSON.

1. Fully restart the MCP client.

Expected: Actor calls authenticate; the 401 is gone.

When this applies

• 401 on every call with a token you typed or copied by hand.
• The stored token looks shorter than the one in the Console.

When it does NOT apply

• Full token with prefix still 401s: the token was revoked; issue a new one.
• record-or-token-not-found: visibility problem, different skill.

Tool and version compatibility

• @apify/actors-mcp-server and direct Apify API calls; the prefix rule is API-wide.

Variant phrasings

Apify 401 with a token I just created

Re-copy it. Fresh tokens are usually broken by a partial copy, not by the platform.

User was not found but the user exists

The message is about the token, not the account. Fix the token string.

Why it happens

The API parses the token format before looking anything up; a string without the expected prefix never matches a credential and returns the generic not-found message. It reads like an account problem but is always the token string.

Edge cases

• Some password managers strip the prefix on autofill; paste into a scratch buffer and eyeball the start first.
• Tokens shown once at creation: if you lost the full string, create a new token rather than guessing.
• Rotate tokens you pasted into shared configs; the old one stays valid until revoked.