Notion API, Getting Invalid_Grant when trying to generate authorization token

TL;DR

Try removing the redirecturi from both the authorize call and the token exchange. The accepted answer reports that dropping redirecturi from both steps returned a success response from the server.

Fix

1. Try removing the redirect_uri from both the authorize call and the token exchange. Expected: You get the expected result; the problem is gone.

When to use

• You are dealing with this situation.
• The symptom matches: Notion API, Getting Invalid_Grant when trying to generate authorization token.

When NOT to use

• Unrelated issues with a different cause.
• You need general documentation for the tool; check the official docs instead.

Compatibility

Reported per the linked source.

Variant phrasings

Notion API, Getting Invalid_Grant when trying to generate authorization token

Why it happens

Stack Overflow question (score 8, has accepted answer): After creating a Notion integration and completing the browser authorize step, exchanging the interim code at the Notion token endpoint returns {"error": "invalidgrant"}. The token request posts granttype=authorizationcode with the code and a redirecturi to https://api.notion.com/v1/oauth/token.

Edge cases

• If your error message differs even slightly, this is probably a different issue; search the exact text.
• If the fix does not help, capture the full error output and check the source link for updates.

Stack Overflow question (score 8, has accepted answer): After creating a Notion integration and completing the browser authorize step, exchanging the interim code at the Notion token endpoint returns {"error": "invalidgrant"}. The token request posts granttype=authorizationcode with the code and a redirecturi to https://api.notion.com/v1/oauth/token. Resolved: Try removing the redirecturi from both the authorize call and the token exchange. The accepted answer reports that dropping redirecturi from both steps returned a success response from the server. So the authorize URL becomes just clientid and responsetype=code, and the token POST carries only granttype and code. If you do pass a redirecturi, it must be byte-identical in both calls and match what is registered on the integration settings page. Source: https://stackoverflow.com/questions/67782515/notion-api-getting-invalid-grant-when-trying-to-generate-authorization-token