ESI: "error": "Character ID mismatch between request path and auth token"

For some reason I am refused access to endpoints on the ESI https://esi.evetech.net portal with the error code in the title. I am using this access from Excel Power Query, this same query used to work a year ago, I have only renewed the OAUTH2 keys.

The character id is from the account I used in the application, and the app has the permissions for the paths I am trying to access, but there seems to be some kind of mismatch with the token…
Any idea?

This happens when you are requesting a resource for a character, e.g. /v5/characters/123/assets/, while using a token that belongs to character 456 or vice versa.

I’d ensure your OAuth2 flow is still up to date based on SSO Authorization Flow | esi-docs. Just going thru the flow for that character again should be sufficient.