Windows 8.1 / Windows 10 breaks my ASP.NET / IIS : "Service unavailable"

Question

With Windows 8.1 finally released to MSDN/Technet today I came across the following issue running my ASP.NET application after doing an in place upgrade with Win 8.1 RTM:

Service Unavailable

HTTP Error 503. The service is unavailable.

• The AppPool has died and shows a status of Stopped

• The IIS log has nothing

• There's a clue is in the Windows Application log which contains this error

  The Module DLL C:\WINDOWS\system32\inetsrv\rewrite.dll failed to load. The data is the error.

How can I recover my IIS to make it work again?

Answer 1

It looks like a simple uninstall and re-install of the rewrite module will do the trick.

Edit: As others have said - try a repair first - if it works then that should be faster.

It doesn't look like the Microsoft Web Platform Installer is able to uninstall it so just go to Programs and Features to uninstall it.

You'll find it listed as IIS URL Rewrite Module 2 and just click the Uninstall button on top.

Then reinstall it from here:

http://www.iis.net/downloads/microsoft/url-rewrite

Make sure your App Pool is started - or just restart IIS and it should all work again.

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Edit: 8/30/16 : A similar but unrelated error can occur if you have the 'new' .NET core installed and update to Win 10 Anniversary edition. See here: https://github.com/aspnet/Home/issues/1583 - Running a repair on VS 2015 Tooling Preview should fix it. Wanted to add it here since the errors are very similar to this answer.

Answer 2

I got this Event Log error after updating Win8.1 to Win10. To fix, go to the Control Panel -> Programs and Features, locate IIS URL Rewrite Module 2, right click and select Repair (it's quick). Next, restart your stopped AppPool(s). Should be OK now.

No need to uninstall nor reinstall.

Gary Davis

Answer 3

Don't need to uninstall. Just do a Repair instead, and it will works.