We had a service with 2.2 with few REST endpoints. We upgraded the framework to 3.3. Deployed the same in on-prem IIS 6.0.
Everything works fine with Swagger. But on calling the same endpoint with multiple threads (using JMETER with 5 user calls at a time). we are getting response
HTTP Error 500.0 - ANCM In-Process Handler Load Failure Common causes of this issue:
The specified version of Microsoft.NetCore.App or Microsoft.AspNetCore.App was not found.
The in process request handler, Microsoft.AspNetCore.Server.IIS, was not referenced in the application.
ANCM could not find dotnet.
Troubleshooting steps:
Check the system event log for error messages
Enable logging the application process' stdout messages
Attach a debugger to the application process and inspect
API is "In process"
[](https://i.stack.imgur.com/osVqi.png)
Tried to enable multiple logs to see if we can debug the root cause. But unable to see any more detailed information. One thing confirmed is Requests are not reaching the Service. Its being thron out before reaching the service.