AFAIK that's a "feature", not a bug. They throttle concurrent requests and return a different error code compared to the on-premises SQL Server.

I just watched a load test hit that issue, the developers cranked up the traffic until the response times were measured in minutes. At that point Azure SQL started throwing errors related to too many concurrent queries.

Compared to just locking up or timing out, it's probably better.

See: https://docs.microsoft.com/en-us/azure/azure-sql/database/re...

And: https://docs.microsoft.com/en-us/azure/azure-sql/database/re...

E.g.: the 4-CPU pool has only 210 Max concurrent workers per pool, but if you think about it, that's over 50 queries running at once per CPU core, which is nuts!