[Note: November 2010 Some recent fixes added]
[Note: September 2009 I am in the process of trying to bring this list up to date. It may not be complete]

There is nothing worse than wrestling with a problem for ages only to discover later that there is already a fix for it. I therefore felt it would be useful to summarise what fixes have been done for ASP.NET 2.0 since it was released. Here are a few important points before you go any further:

  • What is a hotfix? A good description can be found in this article - Description of the standard terminology that is used to describe Microsoft software updates
  • When we ship a fix we always try to minimise the number of files affected. So far, most ASP.NET 2.0 fixes we've released only affect three files: System.web.dll, WebEngine.dll and aspnet_wp.exe. The fixes listed in the first table below all update those files to the version number indicated.
  • Fixes are cumulative. So for example if you install the fix that says it installs version .832 then you are also getting the bug fix that is described in the article that says it installs version .819, .804 etc., etc. That's why I've written the below table in reverse version number order.
  • Check the version number of these files on your system first. If your version number is already higher than the version number indicated in the article then it means you already have that bug fix. If you are getting a problem that sounds like what is described in the article but you already have that fix, then you are probably getting a similar problem or set of symptoms due to some different underlying root cause.
  • If for some reason you don't want that security update but want a more targetted hotfix package for ASP.NET only then the next simplest thing would be to go to the connect site and directly download one of the fix packages for ASP.NET that are available there that includes the fix you are looking for (see below).
  • If you are still not sure what fix you need, are having trouble getting hold of a particular fix, are having trouble installing it or have installed it but it hasn't solved your problem then contact Microsoft Product Support.  Scott Guthrie blogged some time ago about a particular hotfix and wrote an excellent introduction to how to contact support (see "Contacting Microsoft Product Support" on that blog entry).
  • If you are having a specific problem obtaining or installing a fix or with solving some ASP.NET issue please don't contact me directly. Unfortunately I cannot scale up to be a one man support organisation. Please utilise Microsoft’s global support organisation as described above.

 

 

Fixes that affect the three core ASP.NET 2.0 files of System.Web.dll, WebEngine.dll and aspnet_wp.exe

 

(located in \Windows\Microsoft.NET\Framework\v2.0.50727)

KB/Version Comment Description
KB2531385
2.0.50727.5671
(Vista and Win7)
  FIX: You are prompted for credentials when you click a user name on an ASP.NET 2.0-based SharePoint application if FBA is used
KB983465
2.0.50727.5053
 

FIX: You experience high memory usage in the W3wp.exe process when you run an ASP.NET 2.0 Web-based application that receives many requests from mobile devices

KB976765
2.0.50727.4444 (LDR)
XP/2003

Description of the ASP.NET update for the .NET Framework 3.5 Service Pack 1 and the .NET Framework 2.0 Service Pack 2 on Windows XP and on Windows Server 2003: June 8, 2010

KB981201
2.0.50727.4442
XP/2003

A hotfix is available for ASP.NET 2.0 that enables support for extended protection

KB981201
2.0.50727.4438
Vista/2008
Package download

A hotfix is available for ASP.NET 2.0 that enables support for extended protection

2.0.50727.4060   FIX: A System.Runtime.InteropServices.COMException exception occurs when you use COM components in the .NET Framework 2.0 to access form data or querystring data that contains a TAB character
2.0.50727.4028   Description of the hotfix rollup package for ASP.NET 2.0: April 2009
2.0.50727.4013   FIX: A hotfix is available to fix two problems in ASP.NET on IIS 7.0 for Windows Vista and Windows Server 2008
2.0.50727.4013   FIX: Error message when you compile an ASP.NET project that contains many application resource files: "A first chance exception of type 'System.ArgumentException' occurred in mscorlib.dll"
2.0.50727.4013  

FIX: ASP.NET Dynamic menus do not render correctly in IE8 in non-compatibility view

2.0.50727.4013   FIX: You experience very slow performance on an initial request to an ASP.NET Web site after you change the App_Code folder, the bin folder, or the Global.asax file
2.0.50727.4013   FIX: Web clients may have several problems when you access an ASP.NET 2.0 AJAX-enabled Web site
2.0.50727.4013   FIX: Error message when you view a page in design mode after you recompile a .NET Framework 3.5 Service Pack 1-based project: "Error creating control – 'ControlInstanceName [text]' could not be set on property 'PropertyName'"
KB976765
2.0.50727.3614 (GDR)
XP/2003

Description of the ASP.NET update for the .NET Framework 3.5 Service Pack 1 and the .NET Framework 2.0 Service Pack 2 on Windows XP and on Windows Server 2003: June 8, 2010

2.0.50727.3082 XP/2003 List of the issues that are addressed by the Application Compatibility Update for the .NET Framework 2.0 SP2
2.0.50727.3074 Vista/2008 List of the issues that are addressed by the Application Compatibility Update for the .NET Framework 2.0 SP2
2.0.50727.3053 2.0 SP2 /
3.5 SP1
Microsoft .NET Framework 2.0 SP2 (included with .NET Framework 3.5 SP1)
2.0.50727.1433   Microsoft .NET Framework 2.0 SP1 (included with .NET Framework 3.5)
2.0.50727.1378 Beta This is not a released hotfix, however Microsoft .NET Framework 3.5 Beta 2 does update the core .NET 2.0 Framework files including the ASP.NET 2.0 files and therefore includes all the below listed hotfixes. So this may be of interest if you are working with the Orcas betas.
2.0.50727.1373 Beta Windows Server 2008 June CTP
2.0.50727.1320 Beta Windows Server 2008 Beta 3
2.0.50727.1318 Beta Microsoft .NET Framework 3.5 Beta 1
2.0.50727.945   FIX: Error message when you try to run an ASP.NET 2.0 Web application if you do not associate the My_Computer_Zone code group with the "full trust" permission set: "Server Application Unavailable"
2.0.50727.926   FIX: Error message when you run an ASP.NET 2.0 Web application that is built on the .NET Framework 2.0: "The constructor to deserialize an object of type '<custom object>' was not found"
2.0.50727.924   FIX: Error message when you run an ASP.NET 2.0 Web application that is built on the .NET Framework 2.0 after you install the MS07-040 security update: "Type 'System.Web.HttpHeaderCollection' is not marked as serializable"
2.0.50727.924   FIX: The # Induced GC performance counter value increases quickly and CPU usage becomes high when you run an ASP.NET 2.0 Web application that is built on the .NET Framework 2.0
2.0.50727.912   FIX: A RemotingException exception occurs when you compile a large Web site project that is built on the .NET Framework 2.0 by using the ASP.NET Compilation tool
2.0.50727.900   FIX: Blocking problems may occur when you use SQL Server to store ASP.NET session state information for a Web site that experiences high loads
2.0.50727.832   MS07-040: Vulnerabilities in the .NET Framework could allow remote code execution

Although this security update patches the core ASP.NET 2.0 files and therefore includes all the below fixes, it also patches many other files in the .NET 2.0 Framework. Please read the above article before proceeding.
2.0.50727.819 ScottGu blog

Download on Connect
FIX: You may receive an exception when you browse a .NET Framework 2.0 ASP.NET Web application
2.0.50727.819   FIX: Error message if you modify a resource file when an ASP.NET 2.0 application is running: "System.InvalidOperationException The resource class for this page was not found"
2.0.50727.804   FIX: Error message when you try to visit an ASP.NET 2.0-based Web page: "HttpException (0x80004005): '/HandlerTest/WebForm1.aspx/a:b' is not a valid virtual path"
2.0.50727.802   FIX: A Web application that is built by using ASP.NET 2.0 does not use the attribute value that you set in the xhtmlConformance element
2.0.50727.312   Windows Vista RTM Release includes this version
2.0.50727.244   FIX: An InvalidViewState exception is not thrown as expected when you use the Triple DES encryption type to validate the System.Web.UI.Control.ViewState property in the .NET Framework 2.0
2.0.50727.219   FIX: You may receive an "InvalidCastException" error message when you try to debug the dump files for Windows SharePoint Services
2.0.50727.213   FIX: The data in a POST request is truncated to 49,152 bytes when an ASP.NET-connected application receives the POST request
2.0.50727.210 Contained in MS06-056

FIX: Some characters in a text resource may not appear correctly when you try to embed the text resource in a Web application that is built on the .NET Framework 2.0
2.0.50727.174   FIX: Error message when you try to run an ASP.NET 2.0 Web application that includes Web services: "The file <FilePath> does not exist"
2.0.50727.166   FIX: You may experience an unexpected AppDomain restart in an ASP.NET Web application that is based on the .NET Framework 2.0
2.0.50727.103   FIX: The Click event for the associated Button control is not raised when page validation fails in a Web application that was built by using ASP.NET 2.0
2.0.50727.103  

FIX: You receive a ThreadAbortException exception in an ASP.NET Web application that is based in the .NET Framework 2.0 when the Async page directive property is set to true

2.0.50727.80 Download on Connect

FIX: You may receive an InvalidCastException error in an ASP.NET-connected Web application

2.0.50727.62 Download on Connect FIX: You receive an exception error message when you specify a Content-Length HTTP header that is larger than 2 GB in ASP.NET 2.0
2.0.50727.62   FIX: Error message when you try to run a Web application that was built by using the .NET Framework 2.0: "Overwhelming changes have occurred"
2.0.50727.62   FIX: Error message when you try to go to an ASP.NET page by using a URL that contains Unicode characters: "HTTP error 400 'bad request'"
2.0.50727.62   FIX: ASP.NET 2.0-connected applications on a Web site may appear to stop responding
2.0.50727.56   FIX: Error message when you try to browse the root folder of a Web application that is built on the .NET Framework 2.0: "Object reference not set to an instance of an object"

 

 

Fixes that affect System.Web.Mobile.dll

2.0.50727.803   FIX: You may experience a decrease in the performance of a .NET Framework 2.0-based application when you call the System.Web.UI.MobileControls.Style.GetValue method many times

 

 

Fixes that affect AspNetMMCExt.dll

2.0.50727.92   FIX: IntelliSense does not work when you use the MMC Snap-In for ASP.NET or the Web Site Administration Tool to add an existing Web.config file to a .NET Framework 2.0 ASP.NET Web site

 

Fixes that affect System.Web.Extensions.dll

3.5.30729.4030   FIX: Exception error message when you use a virtual path provider to serve a Web page that has a ScriptManager control: "Directory '<file directory>' does not exist. Failed to start monitoring file changes."