0Auth2 keeps expiring despite refresh token

Dropbox currently offers short-lived access tokens, which expire after a few hours, and refresh tokens, which don't expire.

If you need continuous access without repeated manual interaction, you'll need to request "offline" access in order to get a refresh token. The refresh token can be used to programmatically retrieve new short-lived access tokens whenever needed.

We can't offer support for this particular "OAuth2.createService" utility as it's not written by Dropbox, so I suggest referring to the documentation and support resources for that for information on how to use and troubleshoot it. For instance, it's unclear if it automatically requests offline access in order to receive a refresh token (and I don't see your code doing so explicitly), so you should check on that to make sure you're getting, storing, and re-using a refresh token.