Unknown User Error

Hello, starting today we noticed we can no longer open the Workflow Scheduler app. When I open the app from SharePoint I get the following:

Unknown User

Unable to determine your identity. Please try again by launching the app installed on your site.

I’m not sure if permissions changed somehow. Any help would be much appreciated.

Hello @aplitt, we are researching the issue.
Currently, we suppose the issue related to Microsoft update, could you please try to reinstall the app and grant permissions to the app again (https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/add-in-permissions-in-sharepoint#managing-and-troubleshooting-add-in-permissions)

Thank you for your response. I ended up granting permissions to the app yesterday and it is now working again.