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I have a fresh install of Visual Studio Community 2019 on a new computer. I started a web app project, ran it for the first time, and then when prompted to accept the self-signed certificate I somehow managed to click "Do Not Ask Again" and "No".

At this point, when running the web app, I get a ERR_CONNECTION_RESET and can't connect to anything. I've tried deleting and recreating the certificate using advice listed here: Re-Installing Visual Studio 2017 Localhost Certificate, as well as reinstalling VS entirely, but neither worked.

To be clear, I messed up, not Visual Studio. As far as I can tell, there's nothing particular about my set up or environment, and I've built web apps in Visual Studio before, I just clicked the wrong things this time and am trying to undo that without factory resetting this entire PC.

Does anyone have any idea how I can trigger that original prompt in Visual Studio and get a properly signed certificate to run a web application?

[SOLVED]

jeff_hinton
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4 Answers4

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If anyone has this very specific issue again, I'll post what I did to fix it (from this forum thread: https://developercommunity.visualstudio.com/t/cant-debug-aspnet-applications-err-connection-rese/1239592?viewtype=all)

1. In VS: Tools > Command Line > Developer Command Prompt, run devenv /resetsettings (this will also reset some customization settings) Edit: not needed, thanks lex-li!

  1. Remove potentially malformed certificates:
  • In User Certificate Manager (certmgr.msc) AND Computer Certificate Manager (certlm.msc):
  • Personal > Certificates > if a localhost certificate exists there, delete it
  • Trusted Root Certification Authorities > Certificates > if a localhost certificate exists, delete it
  1. Repair IIS 10.0 Express:
  • Control Panel > Programs & Features > Right Click IIS Express > Repair
  • It will ask for a file path o a .msi installation file, but VS doesn't store one for IIS Express
  • Look for a hidden file _package.json in the directory C:\ProgramData\Microsoft\VisualStudio\Packages\Microsoft.VisualStudio.IISExpress.Msi,version=xx.xx.xxxxx.xxx,chip=x64
  • Copy the "url" (which should point to the correct .msi file) in _package.json into the file path asked for by the Repair prompt
  • Verify the repair worked by running netsh http show sslcert ipport=0.0.0.0:44390 in the command prompt (ensure the Certificate Hash field is present).
  1. Restart Visual Studio, debug your application, you should get the same Trusted Certificate prompt you misclicked the first time. (You can check the User Certificate Manager to see a new localhost certificate has been installed correctly)
jeff_hinton
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Simply open the terminal:

dotnet dev-certs https --clean
dotnet dev-certs https --trust
David Bond
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Bazoo Studios LLC
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    This alone didn't solve it for me. I also had to use the VS Installer to repair my VS 2022. Then after a reboot, I launched VS and ran my Web project. VS then prompted me to trust the IIS Express certificate. Then the issue was fixed. – RonC Sep 28 '22 at 18:00
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You can create a self-signed certificate using dotnet dev-certs It'll be stored in your PC's certificate store and VS will use it when scaffolding new projects with SSL support.

https://learn.microsoft.com/en-us/dotnet/core/additional-tools/self-signed-certificates-guide#create-a-self-signed-certificate

Ibrahim Abdelkareem
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  • Thanks for the response. I tried the suggestions listed on that page, scaffolded a new project, and was unfortunately met with the same problem. I ran `dotnet dev-certs https -ep $env:jeff\.aspnet\https\WebApplication1.pfx` followed by `dotnet dev-certs https --trust`, and clicked yes on the prompt that appeared. When running a new web app, I still got a ERR_CONNECTION_RESET message. – jeff_hinton Jun 02 '21 at 19:52
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    The .NET Core self signed certificate is not related to IIS Express's, so your suggestion does not help. – Lex Li Jun 03 '21 at 00:03
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I had issue with SignalR client failing to connect/subscribe to localhost hub in development only, because the localhost dev cert was not a trusted root certificate; likely caused by browser security requirements.

Using 'MMC' export localhost 'ASP.NET Core HTTPS ...' cert from 'Personal Certificates' and import into 'Trusted Root Certificates'.

Jeff
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