Cannot send a DEBUG request .Net Core

Hi, getting this error when trying to Debug .Net Core web app, all was fine yesterday evening, but since morning can't run the app. Did anyone see this error before?

All is fine with the launchSettings.json, it has not been changed. Can it be related to the widnows security settings ? VS works fine


Hello, Aleksandr Madisson.

Could you please clarify, which Rider version do you use, and what kind of framework (.NET Core, .NET Framework etc.) is your project targeting? There's a known issue with .NET Core 2.1 not working in the latest Rider EAP builds: RIDER-53291.


Hi, sorry for delay, was on vacation, both versions can't debug 2020.2.4 and 2020.3 EAP8. Have to use VS for .Net Core projects. All is fine with .Net projects

P.S. Seems i have the same issue or similar






Some updates, to fix this issue I closed Rider, deleted .idea folder and reopened the project by the Rider 2020.2.4, started to Debug fine with the IIS Express.

If to repeat this procedure for the 2020.3 EAP 9 then it will fail for Debug only. Since it's the EAP version, maybe it's fine.


Aleksandr Madisson, could you please share .idea/config/applicationhost.config file from the solution directory before and after opening it in Rider 2020.3 EAP 9?

> Since it's the EAP version, maybe it's fine.

This is not fine: it means it will break for you after 2020.3 release.


One possible reason for the issue could be that Rider 2020.3 switched from x86 IIS Express to x64. Could it be a problem for your project? It is actually quite unusual that you had the x86 version of the ASP.NET Core module available.


Thank you for a quick response, I will be investigating once I get enough free time.


Seems this issue has been resolved in Rider 2020.3.1 EAP. All works, at least for my case.


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