This issue currently applies to ShareGate 8.0 and below and SharePoint Online (because you’re authenticating via the Browser option and ShareGate caches your credentials)
Here’s the scenario, you’re migrating from or to SharePoint Online using ShareGate, so you have to authenticate using the Browser option, as pictured below:
At some point you may decide to change your migration/content access account password, either due to domain policy or because someone leaves and you need to ensure the integrity of your system etc.
You change your password in Windows, which is applied instantly but Office 365 takes until the next Azure Active Directory (AAD) synchronisation window to update the account you use for Office 365/SharePoint Online.
You begin a migration and logon to ShareGate/SharePoint Online using your old password, which is still valid as the synchronisation has not yet taken place.
TIP: At this point you should wait until the password synchronisation has completed between your on premise Active Directory Domain Service (ADDS) and AAD!
You crack on regardless and partway through the migration you begin to get errors because the password synchronisation has now occurred and you migration accounts authorisation is no longer valid. You need to reauthenticate.
You try to rerun the migration but you get an error saying:
Error while attempting to connect to SharePoint: The connection to the SharePoint site failed.
You can clean the cache by going into ShareGate Settings, under System you should see a button saying “Clear Cache” under Local Cache but still you get an error.
Here’s how you manually resolve the issue in a timely manner.
Close ShareGate completely (including Exit from the Windows tray) then rename your Sharegate folder in Explorer. It should be in C:Users[YOU USER]AppDataLocalSharegateuserdatacache. Rename the cache folder to anything for example cache.old. Then reopen ShareGate, it should recreate a new folder at the same location and prompt you to reauthenticate.