ASP.NET Web Development Server Stops Working

ASP.NET Web Development Server Stops Working

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A Windows Defender and Microsoft Forefront Client Security signature file (1.53.256.0) was released at 8:45 PM (PST) on March 9, 2009 to address a Win32/PossibleHostFileHijack issue.  This update modified the hosts file to prevent malicious redirection of websites.  As a result, the entry for localhost may have been removed from the hosts file.  When this entry is missing and a site is launched in the ASP.NET Web Development Server (aka Cassini) via Visual Studio, Internet Explorer displays “Internet Explorer cannot display the webpage”.

To resolve this issue, open C:\Windows\System32\drivers\etc\hosts and add an entry for localhost:

127.0.0.1       localhost

A new signature file (1.53.288.0) was released at 8:57 PM on March 9, 2009 that does not affect the localhost entry.

More information about this signature file and additional details about the fix can be found at http://www.microsoft.com/security/portal/Entry.aspx?name=SettingsModifier:Win32/PossibleHostsFileHijack&threatid=1758608427027806866 under the “Recovery” tab.

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  • A Windows Defender and Microsoft Forefront Client Security signature file (1.53.256.0) was released at

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  • I wondered what all the comotion was about.

  • yeah, I ran into this today and wasted half the day before I figured it out.

    Thanks for the post.

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  • After (probably) an update of ESET NOD32 I got the same message. In my case the solution was to comment OUT this line the hosts file

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    Everything works great now, without a localhost entry...

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  • Hi Scott,

    That's really a good update. Thanks for the info. I was struggling a few days with this problem.

    Thanks ,

    Thani

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  • Just a quick heads-up for you all, as I assume this may affect many readers of this blog. It appears Microsoft made a boo-boo with a recent Windows Defender signature file that has made the ASP.NET Development Server stop working for many folks.

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