OAuth2 Refresh Token Invalid

[michael5w]

I've had my app running for a couple months smoothly on OAuth2.  Just yesterday (10/1), I stopped being able to pull new data and noticed the error was in fetching a new access token using my stored refresh tokens.

The error is: 

{"errors":[{"errorType":"oauth","fieldName":"refresh_token","message":"Refresh token invalid: XXXXX"}],"success":false}

I dont store access tokens, I store the refresh token, and refresh on my server every time I get a notification, which is one part that might seem funny, but again everything was working until yesterday.  Any ideas?

[JeremiahFitbit]

I'm guessing the refresh token was used to refresh the access token and your application didn't save the new refresh token returned for some reason.