I just spent hours debugging this - but when trying to pair up with the Yahoo OAuth for their API, then OAuth Token returned is MUCH larger than the 255 characters allowed in
I had to drop the tables and tweak the schema to change
token_key to a text column and also drop the database indexes on it. Unfortunately, this will impact performance. I'm not really sure if there is a better approach to this.
The key I got back was 814 characters (not sure if they vary).