Unable to start debugging on the web server. Operation not supported. Unknown error 0x800040005

Question

Getting this on Windows 10 Pro, Visual Studio 2017. ASP .NET Framework 4.6

Note enabling 32-Bit Applications on IIS did not resolve the issue — navarq, Oct 18 '17 at 09:11
Killed my environment - I am running SharePoint and setting this loses it's mind in IIS (I suspected it would as SP is 64 bit) - the result was interesting - it lost all of the applications. Change back fixed SP but not Visual Studio; in the end it looks like VS 2017 installation broke the environment. — David Sterling, May 28 '18 at 10:43
If this could help --> https://stackoverflow.com/questions/4653236/unable-to-start-debugging-on-the-web-server-could-not-start-asp-net-debugging-v — Gayatri, Nov 14 '18 at 19:46
Doesn't appear to me web server or .net framework, or VS version related. I received this error attempting to hit a break point on a Xamarin Android project. Only thing in common was win10 pro. — axa, Jun 14 '23 at 06:49

score 9 · Answer 1 · answered Nov 26 '19 at 17:51

9

I had this issue and found that removing a https rewrite rule to force www fixed it for me.

answered Nov 26 '19 at 17:51

WhiteleyJ

1,393
1
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I have not experienced the issue again for quite a while hence cannot test whether or not this works or not. – navarq Dec 03 '19 at 10:38
1

My issue was caused by a URL Rewrite rule that forced https – MonkeyDreamzzz Jan 16 '20 at 12:51
Sometimes I feel like this bug comes up when IIS just needs to recalculate some internal configuration. – WhiteleyJ Jan 17 '20 at 15:09

score 1 · Accepted Answer · answered Oct 17 '17 at 11:12

1

Using the task manager to close all Visual Studio processes currently running and restarting visual studio fixed the issue.

answered Oct 17 '17 at 11:12

navarq

1,075
2
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1

Restarted my computer and still doesn't work :( – BVernon Feb 28 '21 at 20:13

score 0 · Answer 3 · answered Sep 22 '22 at 16:17

Another thing to check for, in our case our live config had the DEBUG verb denied:

<security>
  <requestFiltering removeServerHeader="true">
    <verbs>
      <!--disable DEBUG verb-->
      <add verb="DEBUG" allowed="false" />
    </verbs>
  </requestFiltering>
</security>

score 0 · Answer 4 · answered May 23 '23 at 18:35

This answer was first described here.

This is most likely a problem with URL Rewrite rules redirecting the DEBUG request Visual Studio sends to the Project Url:

Request URL: https://Project.Url:443/debugattach.aspx
HTTP_METHOD: DEBUG

In our case, all .aspx requests were being redirected to index.aspx so we added this:

<rule name="DebugBypass" stopProcessing="true">
  <match url="^.*$"/>
  <conditions>
    <add input="{HTTP_METHOD}" pattern="^DEBUG$" />
  </conditions>
  <action type="None"/>
</rule>

Worked like a charm.

FYI - Discovered this by turning on Failed Request Tracing for the Project URL and evaluating the trace log.

Unable to start debugging on the web server. Operation not supported. Unknown error 0x800040005

4 Answers4