HTTP Error 503. The service is unavailable under simple ASP.NET 4.0 web site

Question

Something strange happened on my local laptop: my web site that worked locally for a long isn't launched...

Trying to localize the problem I've created a simple web site with 'index.html' file only. It works fine under ASP.NET 2.0, but when I switched App Pool to use 4.0 - it stopped to work.

When I open web site in browser it shows the following error:

Service Unavailable

HTTP Error 503. The service is unavailable.

And causes App pool to stop work also... In the system event log in "applications" section I have:

The worker process failed to initialize correctly and therefore could not be started. The data is the error.

Please advise. Can't find anything related in Google... :(

P.S. I have VS2010, Windows Vista x64, last updates installed, VS SP1 is also installed...

Answer 1

I had to start the application pool that was set for my website and was automatically stopped on some error. (IIS (7.5 in my case)->Application Pools->Start stopped application pool.)

Answer 2

I've reinstalled .NET 64 - that helped.

P.S.

It seems like either some files in "C:/windows/Microsoft.net/Framework64/v4.0.30319/" folder or I removed them myself (VS sometimes complains on files in "ASP.NET Temporary files" and their deletion helps)... Probably I didn't pay attention that those folder not a temporary...

P.P.S.

In this case, why VS complained on files in "C:/windows/Microsoft.net/Framework64/v4.0.30319/" folder... ok, now it's hard to say.