Resolved
This incident has been resolved. Login via Slack is operating normally again, and no further action is required.
Identified
Some customers on Slack Enterprise Grid who sign in with Slack are seeing Slack-originating errors when logging in.
We've raised this with Slack and are monitoring for a fix.
Customers using SAML sign-in aren't affected.
Alert ingestion and our On-call product's paging functionality are unaffected.