Customers who were exceeding their concurrency limit during this outage may be encountering strange errors in their crawls.

This is due to the nature of the outage affecting our concurrency limiting system, causing unique jobs to be inserted into a separate per-team concurrency queue multiple times. When these jobs are promoted from the concurrency queue into the main queue, they retain their IDs, which causes a violation of the unique ID constraint.

A fix for this issue is now deployed.