Windows Server 2012 R2, IIS 6.2 build 9200. We’re hosted in Azure, and lean heavily on Redis for caching.

Received an IIS error on our site yesterday which coincided with ~1k concurrent users:

max concurrent user limit reached

In IIS settings under

Advanced settings
Maximum Concurrent Connections
property is set to

What else might cause this error? It seems to of brought our website down and forced us to reboot to fix. Our pages all do some sort of heavyish work (anywhere from 20ms to 100ms in rendering time).

Anonymous Asked question May 13, 2021