How to solve “Microsoft Visual Studio (VS)” error “Unable to connect to the configured development Web server”

I fixed the problem with deleting .vs folder on project folder.

• Close VS projects.
• Delete .vs folder on project folder that includes applicationhost.config file.

VS will generate new config for this project.

Opening Visual Studio as administrator will fix the problem.

I solved the error by changing the port for the project.

I did the following steps:

1. Right click on the project.
2. Go to properties.
3. Go to Server tab.
4. On tab section, change the project URL for other port, like 8080 or 3000.

Good luck!

We solved this problem with deleting .vs folder on project folder and deleting temporary ASP.NET files.

1. Close the Visual Studio.
2. Delete .vs folder on project folder that includes applicationhost.config file.
3. Delete temporary ASP.NET Files located: C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root

Solution 1

If you use a newer version of Visual Studio, you may not have this problem. I'm currently using Visual Studio 2015 and it works great.

Solution 2

You can solve this problem by changing the project's port number.
Because the reason is a port number conflict with some other application.

I had the same issue and fixed by doing that (by changing the port number).
I had solved this here : Changing project port number in Visual Studio 2013

If you use a different version of Visual Studio; you may also change the port number by project's Properties Window in Solution Explorer.

For me I tried a few of the above - run as administrator, check firewall.

For me it was the IIS Express configuration. A little bit of a "just get it working" fix without much investigation, but deleting the folder IIS Express is located under

C:\Users\UserName\Documents\iisexpress

Not sure what caused the issue for my VS2013 - but I am constantly flipping between VS2013 sites in IIS and IIS Express.

NOTE: When I forget to run VS2013 as Administrator, my Local IIS project gets inserted in the IIS Express applicationhost.config file, which fails to open the web project. Which is really frustrating.

Worked for me in VS2003 and VS2017 on Windows 8

1. Run the command in CMD with admin rights

   netsh http add iplisten ipaddress=::

2. Then go to regedit path [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters] and check if the value has been added.

For more details check https://www.c-sharpcorner.com/blogs/iis-express-failed-to-register-url-access-is-denied

I am using visual studio 2015. Deleting .vs folder in the project folder helped me to fix this. You must close the visual studio first.

I solved this just now, in the system tray (bottom right) you can click ion the IIS icon and stop the current site, then it allowed me to run.

I just encountered and resolved this in VS2013 on Windows 7. It is a Web Application Project that doesn't use SSL. But when I examined the Properties Window (F4), SSL was enabled. Setting SSL to false resolved the issue.

However, when verifying before posting this answer, turning it back on did not cause a recurrence of the problem. So it might be that anything that writes to that preferences resolves the problem, rather than the details of what was written.

I solved this by restarting my computer. I'm guessing that this port was being occupied by a process that needed to be killed.

If you've tried many ways and still have this problem, take a look at your firewall settings and make sure it does not block Visual Studio or IIS !!

This worked for me!

I tried almost all the options above, none of them worked for my scenario. Finally I was forced to uninstall IIS Express, re-start the machine, and install the same version again from Microsoft.

Anyway thanks for all the suggestions above.

This happened to me on Windows 7 and VS 2013 while viewing a project on the browser after build. I only had to close the browser "Chrome" then made sure that the port is not in use in my Network Activities using some utility then tried again and worked without any problem.

Additionally to Bruno's answer I ended up registering the same port for localhost. Otherwise VS2015 was giving me Access Denied error on server start.

netsh http add urlacl url=http://localhost:{port}/ user=everyone

May be it's because I have binding for localhost in aplicationhost.config also.

Visual Studio 2015, Windows 10, project source control was managed in TFS Online.

None of this worked form me, issue appeared after a reformat of Windows 10 and subsequent reinstall of VStudio 2015. I mapped projects to the same folder (residual folders and files were still there.)

Deleting the entire old project (specifically the .VS) and then remapping it fixed everything.

Just update Visual Studio, this is the simplest solution that worked for me.