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ASP.NET Web Development Server Stops Working

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.

Posted: Friday, March 13, 2009 9:01 PM by WebDevTools

Comments

What's New said:

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

# March 13, 2009 6:04 PM

DotNetKicks.com said:

You've been kicked (a good thing) - Trackback from DotNetKicks.com

# March 13, 2009 6:20 PM

DotNetShoutout said:

Thank you for submitting this cool story - Trackback from DotNetShoutout

# March 13, 2009 6:24 PM

Dan said:

I wondered what all the comotion was about.

# March 13, 2009 9:45 PM

Zack said:

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

Thanks for the post.

# March 13, 2009 11:54 PM

Kirk Evans Blog said:

If you are suddenly unable to debug ASP.NET apps using the ASP.NET Development Server (aka “Cassini”),

# March 14, 2009 7:03 AM

Hugo said:

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

::1             localhost

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

# March 16, 2009 2:54 AM

Expression Blend and Design said:

When you preview a Silverlight application in Expression Blend, we run the ASP.NET Web Development server

# March 16, 2009 3:35 AM

Thanigainathan.S said:

Hi Scott,

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

Thanks ,

Thani

# March 16, 2009 8:14 AM

Ruminations from the Expression Web support team said:

Problem When you try to preview an ASPX or PHP page in Expression Web 2, which uses the built-in Microsoft

# March 16, 2009 11:24 AM

Anna Ullrich said:

When you use the Preview in Browser feature in Expression Web for an ASP.NET or PHP page, Expression

# March 16, 2009 2:00 PM

Expression Web team blog said:

When you use the Preview in Browser feature in Expression Web for an ASP.NET or PHP page, Expression

# March 16, 2009 2:00 PM

LeeDumond.com said:

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.

# March 19, 2009 9:33 PM

DDL said:

ASP.NET Web Development Server -

# March 30, 2009 4:24 AM

Vijay Kodali's Blog said:

Visual studio Development Server problem in Vista

# April 7, 2009 5:20 PM

johnny said:

My visual web developer stopped working also yesterday. I made no changes to my system what soever. I'm trying a basic hello world web app and IE just says connection but never connects. I checked the hosts file but its fine. This is frustrating. It was working fine the other day. I have Vista, VSS2008.

# April 10, 2009 3:56 PM

WebDevTools said:

Hi Johnny,

   I am sorry to hear that you are facing this issue...  From your comment it seems like you are using Visual Studio Web Development Server as opposed to IIS... Is that correct?

   Can you drop me a line at Vishal.Joshi@Microsoft.com and we can discuss further on what might be going on...  In all honesty, we have not heard of any issues outside of the host file one so I too am curious to understand what might be going on...

  Please do also confirm whether you are using VWD 2008 express editio or full VS skew...

-Vishal

# April 10, 2009 11:25 PM

Johnny said:

Hi Vishal

Thanks for responding to my post. I'll go ahead and also send you an email in addition to this comment. Perhaps this might help someone else. I am using Visual Studio 2008. I'm not using IIS and instead using the asp.net development server. It was working fine until around april 10th. If i debug using firefox it works fine. Firefox quickly resolves my localhost url. If i debug using IE, IE wont connect at all. It just says connecting forever. The URL is

http://localhost:49201/Default.aspx.

I then replaced the localhost with 127.0.0.1 and it resolved the url. I checked my hosts file and its fine. I'm using windows vista. I'm now checking all my internet settings but they all are set for a wireless connection. I use time warner cable with a linksys router. I also tried disabling windows defender,all anti virus programs and I tried turning off windows firewall. IF you could help me that would be awesome.

# April 13, 2009 3:01 PM

Johnny said:

Hi Vishal

Thanks for responding to my post. I'll go ahead and also send you an email in addition to this comment. Perhaps this might help someone else. I am using Visual Studio 2008. I'm not using IIS and instead using the asp.net development server. It was working fine until around april 10th. If i debug using firefox it works fine. Firefox quickly resolves my localhost url. If i debug using IE, IE wont connect at all. It just says connecting forever. The URL is

http://localhost:49201/Default.aspx.

I then replaced the localhost with 127.0.0.1 and it resolved the url. I checked my hosts file and its fine. I'm using windows vista. I'm now checking all my internet settings but they all are set for a wireless connection. I use time warner cable with a linksys router. I also tried disabling windows defender,all anti virus programs and I tried turning off windows firewall. IF you could help me that would be awesome.

# April 13, 2009 3:05 PM

Siva said:

You are a life saver, searching for the solution to this problem for nearly a month or so.

Thanks again.

# May 6, 2009 10:44 AM
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