DriveWatcher uses Google-generated tokens to generate the notifications you receive via email or Hangouts Chat bot. However, these tokens can become invalid, causing the application to fail when generating the notifications. The reasons for the tokens to become invalid are:
If you want to continue using DriveWatcher, you just need to open DriveWatcher and renew the permissions the application needs to work normally by clicking on the «Allow» button. You do not need to worry about your subscriptions, they will remain untouched and will be available when you renew your permissions.
In case you are not interested in using DriveWatcher any longer, please contact email@example.com so we can remove all your remaining information.
NOTE: a token is a code that authorizes an application (in this case, DriveWatcher) to get some information about the user (for example, the activity of a user’s Google Drive folder).