Dropbox is in the process of changing their authentication method for their API. This change is nullifying all existing authentications by September 30th and will require you to re-authenticate your Dropbox connection with ClearCheckbook if you're currently using Dropbox for your Automatic Backups.
The process to re-authenticate is extremely simple and can be done by logging into your account and then clicking on Tools at the top of the page. Next, click on the Automatic Backups link and then the red 'Cancel Automatic Backups' button. After that, click on the green 'Authorize Backups to Dropbox' button and follow the instructions to authenticate Dropbox with ClearCheckbook. Note: It might not have you approve the connection again, but simply redirect you back to ClearCheckbook. If that's the case, everything still worked correctly if you see the Automatic Backups Enabled text.
Once you do that, your backups will continue working past the September 30th cutoff date. If you don't re-authenticate before September 30th, ClearCheckbook won't be able to access your Dropbox account to save your backups.
This change does not affect Google Drive or OneDrive and will not remove any existing backups to your current Dropbox folder.
If you want to learn more, you can read up on the Refresh Tokens
change in this blog post: https://dropbox.tech/developers/now-available--scoped-apps-and-enhanced-permissions