Canvas stores your credentials on your machine.  From time to time, these credentials can be revoked or can simply expire, requiring you to re-authorize your account before Canvas can continue using it.  

If you've ever received any of the following errors, chances are you need to refresh your authorizations: 

• OAuth Tokens not available Google docs access
• Unknown Error No authorization 
• Management API V3.0 error:Unable to refresh token:The remote server returned an error: (400) Bad Request. Unable to retrieve Google Account information
• Google Docs api error – Google Sheets import: The remote server returned an error: (400) Bad Request

To refresh your token, go to Accounts > Authorize New Account and select the appropriate credential.  Complete the authorization process, then refresh or re-run your Canvas.  You should now be back in action. 

If for some reason that didn't work, go to Accounts > Manage Accounts then select the account that is causing issues and click Remove. 

Then go back to Accounts > Authorize New Account and re-authorize the account.  

If you are using either Cloud or Server Automation, be sure to regenerate your password files so that the new tokens can be used in your automation tasks. 

For each file that is using a credential that has been expired or that requires an update, perform the following: 

1. Open the file
2. Go to the Automation menu and select "Generate password file for this canvas"

3.   Overwrite the existing password file for that Canvas both on your desktop and, if applicable on your Server.  

If you are using Cloud Automation, click on the Cloud Automation menu, select the appropriate package, and click "Sync". Follow the wizard to upload the package again, including both the ACC and password files.