.NET Framework 1.1 and 2.0 Side-by-Side (SxS)

December 18, 2006 Update: You may find my post on .NET 3.0 compatibility useful.

As a part-time systems engineer, I was very concerned about possible negative effects of installing the .NET Framework 2.0 side-by-side with 1.1 on our Windows Server 2003 boxes that run things like SharePoint Portal Server, Windows SharePoint Services and Exchange 2003.  I’ve searched and searched, and it seems like Microsoft is making little effort to document .NET Framework 2.0 compatibility with their server products.

It helps to understand how different types of executable code load the Framework.  Unmanaged applications that host the Common Language Runtime (CLR), that is, non-.NET applications that manually load the CLR in order to run .NET code, always load the newest installed version of the .NET Framework by default.  This behavior directly impacts SharePoint Portal Server, as one example, in a negative way.  Some unmanaged executables in SPS host the CLR, so as soon as you install 2.0 and restart the SPS apps, they will load 2.0, not 1.1 as they were designed and tested against.  BAD!

Fortunately, managed applications behave better.  A managed application that was built against 1.1 will continue to load 1.1, as long as 1.1 is installed.  (On Windows Server 2003 you don’t have a choice, but on other OS’s you can uninstall 1.1.)  A managed application that was built against 2.0 will only load 2.0.  If you uninstall Framework 1.1, your 1.1 managed app will now load 2.0 instead.

Confused?  When Microsoft doesn’t document which unmanaged apps host the CLR, the bottom line is that you need to be careful installing 2.0.

If you identify an unmanaged app that hosts the 1.1 CLR and you want to install Framework 2.0, there is a way to force the unmanaged app to load the old Framework:

  1. Locate the unmanaged EXE, and in the same directory, create (or edit) a text file called <unmanagedexename>.exe.config.  Ex: myapp.exe needs myapp.exe.config.
  2. Paste this text into the new text file (or merge it into the existing file; you may already have <configuration> and/or <startup> elements):
    <?xml version =”1.0″?>
        <supportedRuntime version=”v1.1.4322″ />
  3. Save the config file and start or restart the EXE or service

Installing the 2.0 Framework without adding or updating the config files will affect SharePoint Portal Server and BizTalk Server 2004.  BizTalk Server 2006 natively runs on, and requires, .NET Framework 2.0, and runs just fine with .NET Framework 3.0 as well.

To safely install 2.0 on your BizTalk 2004 server:

  • Add (or update) a config file for each EXE in your BizTalk 2004 installation folder
  • Reboot or restart all BizTalk services
  • Review Microsoft’s KB
  • After installing Framework 2.0, ensure that all BizTalk Web services remain configured to run under ASP.NET 1.1.

To safely install 2.0 on your SPS servers:

  • Add (or update) a config file for each EXE in your SPS installation folder
  • I recommend installing WSS 2.0 SP2, which explicitly supports ASP.NET 2.0, and then SPS 2003 SP2.  If you are not ready to upgrade, you can still add the config files and safely install 2.0 on SP1 or earlier.
  • After installing Framework 2.0, ensure that all SPS portal Web sites remain configured to run under ASP.NET 1.1.  SPS SP2 does not support ASP.NET 2.0, even though WSS does.

To safely install 2.0 on your Exchange 2003 servers:

  • Exchange Server 2003 doesn’t appear to host the CLR, so it should be safe to install 2.0 on Exchange front-end or back-end servers.  I installed it on our front-end server with no issues.
  • After installing Framework 2.0, ensure that the OWA Web site remains configured to run under ASP.NET 1.1 (IIS Admin, site properties, ASP.NET tab).

Installing .NET Framework 2.0 installs ASP.NET 2.0.  By default, this will not change existing IIS Web sites to 2.0 — they will remain set to 1.1/1.0.  You can control this in IIS Admin in the site properties under the new ASP.NET tab.  Do not try to mix ASP.NET 1.1 and 2.0 apps within a single AppPool on Windows Server 2003.  Create separate AppPools for each version.

Office 2003 is unmanaged but does host the CLR, so it may also be affected by installing Framework 2.0.  There are known issues with Office 2003 when loading add-ins, smart tags or smart documents created with .NET Framework 2.0.  There is also a related VS2005 update for Visual Studio 2005 developers.

Visual Studio .NET 2003 developers may experience trouble in certain cases after installing Framework 2.0.  One such issue is fixed in .NET Framework 1.1 SP2.

The Framework documentation briefly, and poorly, discusses the side-by-side issue here.

I would appreciate comments on this post!  Is it helpful?  What information can I expand on?  Are there other issues that you are concerned about or have experienced?


  1. Hi,

    Suppose I have a .net 2 app which references a .net 1.1 dll, what happend then? does the 1.1 dll know it should use the 1.1 framework?



  2. Hi Tomer, if a .NET 2 app references a .NET 1.1 DLL, the 1.1 DLL will be forced to run under 2.0. You run the same risk of it maybe working, maybe not as you would with an entire 1.1 application running under 2.0. You’ll want to retest any code that lives in the 1.1 DLL in your 2.0 app to make sure it is working as expected. Only one version of the CLR may be running in a single process, so if your application is 2.0 then any other .NET code in that application’s process will also run under 2.0.

  3. Hi Thomas,

    We currently have our application in 1.1. This involves a server application. So if i migrate it to 3.0 (which we are preferring over 2.0), would it still work if any client is still using 1.1?

    Thanks in advance.

    Wonderful ideas man, way to go, helps a lot :)

  4. Remote_User, the answer to your question depends on how the clients interact with your server application. Since you mentioned the clients using 1.1, I assume this is not a website but some kind of client/server app. If you were to upgrade the server app to .NET 3.0 while keeping the same client/server communication code, you would have less chance of issues than if you also rewrote the communication code with WCF in .NET 3.0. Again, it really depends how the clients interact with the server.

  5. Hi,

    Yes, so maybe we could actually use this WCF right, after all if we are migrating to 3.0.

    If the current communication is based on DCOM model, will this be something really big, like needeing a re-architecture for the communication model?

    Thanks a lot !

  6. Hey and one more thing, this 3.0 is available for licensed use now?


  7. Remote_User, yes, .NET Framework 3.0 was officially released last November. If you are currently using DCOM and thinking of converting to WCF, it’s likely you would want to revisit the design of your communication model. WCF supports SOAP Web services, MSMQ, Named Pipes for inter-process communication and TCP peer-to-peer for cross-machine communication. No matter which you choose, you design your interface and service virtually the same way, then configure WCF to link your interface and the specific protocol. However, if your clients are expecting DCOM, you will end up changing both your clients and the server.

    WCF has some integration points with Enterprise Services, for example with transactions: http://msdn2.microsoft.com/en-us/library/aa751796.aspx. Please see netfx3.com for more information about all of the .NET 3.0 components.

    Thanks for reading!

  8. Thanks a lot ! Really appreciate your inputs.

  9. HI Thomas,

    I’ve have a .NET Framework 1.1 compiled DLL (COM enabled say MyDll.dll) Which is written in VB,I Use this Dll from a VC (Eg Myapp.exe) even though i supplied (Myapp.exe.config) with the <supportedRuntime> configuration settings i have problems executing Myapp.exe when .NET Framework 2.0 is installed. What should be the format of the config file, Please Help.

  10. Srinivas, is the VC++ application managed or unmanaged C++? The format of the app.exe.config file is exactly that found in my original post above.

  11. Hi,

    I have a project (A)which uses dlls from other project (B) , so if i want to step into the code of B while running A, i.e. debug through it i need to copy over the .pdb files of B into A’s Bin directory right? But this is not helping. Doesn’t that work?


  12. Hi Remote_User, you might try the other way around. Open project B and tell it to start the debugger using the EXE of A. You can also use Attach to Process if it just refuses to pick it up. It depends a little on how the DLLs are used, but it seems like your original statement should be true too.

  13. Hi Thomas,

    We have developed our web application on .Net 1.1/windows 2003. Now, we wanted to migrate the application to .Net 2.0 but we don’t want to keep both 1.1 and 2.0 on the box, hence planning to remove the 1.1 from windows 2003. Is that possible? or If yes, would this setup(having only 2.0) create any issue in the future.

  14. Hi Jack, you could certainly disable or remove .NET 1.1 on Windows Server 2003 using unsupported methods, but what do you hope to gain? You said you are working with an ASP.NET app, so once 2.0 is installed you can simply instruct IIS to run your site using .NET 2.0 in IIS Admin. Other than a bit of disk space wasted, there is no real downside to having 1.1 present if your apps are for 2.0. A 2.0 app cannot run on 1.1, so if your apps are all for 2.0 nothing will ever load the 1.1 Framework.

    Removing it would probably be a bad idea if you ever had to call Microsoft Product Support for an issue on your server. Windows Server 2003 R2 now ships with .NET Framework 2.0 preinstalled.

    If you have no 1.1 ASP.NET web apps, you can go into Add/Remove Windows Components and uninstall ASP.NET under IIS — that is for 1.1. If you still want to try removing 1.1 entirely, this article may give you some ideas: http://support.microsoft.com/kb/830646/. You could see if this tool will remove it: http://blogs.msdn.com/astebner/archive/2005/04/08/406671.aspx.

  15. Hi Thomas,

    I had .NET 1.1 on my system, still do have it and then yesterday i installed IIS. Does this require re-installation of .NET?? :(

  16. Hi, I’ll assume you are asking because ASP.NET generally doesn’t work when you install in that order. You don’t need to reinstall the .NET Framework to get it working. Run “\WINDOWS\Microsoft.NET\Framework\v1.1.4322\aspnet_regiis.exe -i” to install ASP.NET in IIS. Hope that helps.

  17. Hi Thomas,

    Does either of this impact the ASP .NET State Service? Because, after installing IIS and FW 1.1 the service won’t start because the path for the executable “aspnet_state.exe”, is not “\WINDOWS\Microsoft.NET\Framework\v1.1.4322\” but “\WINDOWS\Microsoft.NET\Framework\v2.0.5….\”. I haven’t installed FW 2.0 why could this be happening?


  18. Hi — running the .NET 1.1 version of the aspnet_regiis command should also register the ASP.NET state service. If you’re saying that the registry has a path to the 2.0 Framework folder for the aspnet_state.exe service, then you must have at least had 2.0 installed at some time or another. You can always run the 2.0 version of “aspnet_regiis.exe -u” to uninstall it, and then run the 1.1 version of “aspnet_regiis.exe -i” to install 1.1.

  19. Hi,

    Thanks for the suggestions :)

    I had a question regarding the “Process.PrivateMemorySize” etc under the Process class in System.Diagnostics. I tried several of these for a process (wanted to check the memory usage) which runs currently on my machine and compared that with that being displayed on the Windows Task Manager. None of them matched to what was there in the Task Manager.

    Which property in the Process class should i use to get the as far as possible accurate memory usage and which may turn out to be as the one in the task manager?


  20. Hi,

    The Mem Usage column in the Task Manager matches that to the WorkingSet property. But the VM size doesn’t match the PrivateMemorySize, or even VirtualMemorySize ! Actually, PrivateMemorySize property gets to the closer value.

  21. I am using .NET 1.1 and am trying to create symbolic link for files. I want to create a new file programmatically using C# and then link it to an existing file much like a soft link/symbolic link in Linux. This feature is not present?

    The DataFormats.SymbolicLink seems to be a Read-Only propery.


  22. No, but you can use P/Invoke to call the Win32 API directly — CreateSymbolicLink(). However, this is a new API with Windows Vista and Windows Server 2008. Maybe you could accomplish what you need with a shortcut?

  23. I needed to do that programmatically :( i don’t think i could manage with creating a shortcut from a program.

  24. Hi, Thanks for the info.

    I have another. slightly related problem. Say i have a .Net 2.0 dll exposed as a COM dll and i want to use it in vs2003, i know you can force it to run using the config file in .Net 2.0.

    I am thinking about DCOM so that it runs as a separate process, in that case you dont need to do a config file? Any idea how to expose the same .Net 2.0 dll as a DCOM exe?

    any other ideas?


  25. Nothing built for .NET 2.0 can run under .NET 1.1, and configuration cannot change that. You can force a .NET 1.1 app to run under 2.0, and then you’d be able to load your DLL in-proc, otherwise you’re looking at cross-process in one form or another. You have a number of options — expose your new code as a web service (instead of COM) and call the service from the 1.1 app; use the built-in System.EnterpriseServices classes to run as a hosted COM+ object — in the Component Services MMC you can choose to run as a “Server application,” which will automatically provide you a new process; force the 1.1 app to run under 2.0 and see if you run into any issues. I hope that helps!

  26. I’ve got VS 2003 with Framework 1.1 on my dev machine. I’m coding for Microsoft Speech Server R1 which requires that configuration (coded in C# and ASP .NET). Meanwhile, I’d like to tinker with, and beef up my C# skills. As long as I don’t mess with the servers, can I install Framework 2.0 (or 3.0) and maybe VS 2005 side by side on my dev machine, without affecting the code I compile for the VS 2003 1.1 servers?

    Hoping this isn’t an obvious issue, but I’m largely self taught on VS .NET.



  27. Mike, you can install both versions of Visual Studio side-by-side and continue to use 2003 for your current code. There can be a couple of minor side effects, but nothing too bad. Here’s a link regarding side-by-side use: http://msdn2.microsoft.com/en-us/library/ms246609(VS.80).aspx. Another great option, since you just want to learn and play, are the ready-to-run Virtual PC virtual machines for evaluation of 2005 or 2008: http://msdn2.microsoft.com/en-us/aa972637.aspx. That way you can do anything you want to it and not have to worry about your main dev configuration. Thanks for reading.

  28. Hi, Thanks for all the great info. I read every post hoping to find my particular scenario. Unfortunately, I didn’t. I have a windows user control created using .net 1.1 that is displayed in ie using the <OBJECT> tag in an asp page. Recently, .net 2.0 was installed on the client machines. The user control now displays an error that tells me it’s trying to load .net 2.0. I tried the <dll_name>.config, but that didn’t work. Also, IIS is configured to use 1.1. Is it a 2.0 Framework configuration issue? Can I just upgrade the user control to 2.0? Any ideas?

  29. Thanks Mike. Based on what you wrote, I assume this is an ActiveX control? You wrote that it is displayed from IE using an <OBJECT> tag in a non-.NET ASP page, so I assume it must be COM/ActiveX. Since this is a client-side issue, IIS is irrelevant.

    IE is hosting the .NET Framework runtime, so it picked up 2.0 when it was installed. iexplore.exe.config on every client machine is where you would have to override it — unrealistic unless you have control over all of your clients. Of course, if you upgrade it to 2.0 then your clients without 2.0 will fail, so the problem will reverse itself.

    I haven’t addressed this particular issue before, but I think you would almost have to have two versions and use JavaScript in the page to determine which version to load via the <OBJECT> tag based on the installed .NET Framework version. Or — IE generally embeds the .NET version in the HTTP request, so you might be able to look at that and send back an <OBJECT> tag with the correct version, one that is written for 1.1 or one written for 2.0.

    It’s possible that I’m off track since you didn’t post the exact error message, but I hope that gives you something to work from.

    Thanks, Tom

  30. Thanks for the quick reply. Yes, it is an ActiveX control. The error is: System.Security.SecurityException: Request for the permission of type ‘System.Data.OracleClient.OraclePermission, System.Data.OracleClient, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089′ failed. After the stack trace is:

    The action that failed was:


    The type of the first permission that failed was:


    The Zone of the assembly that failed was:


    Fortunately, this particular control is only used by a few clients (less than 5). Could it be specific to System.Data.OracleClient?

    Thanks, Mike

  31. Mike, I see, that’s a bit different than what I assumed. Your ActiveX control might function fine on 2.0 — often 1.1 code is OK on 2.0 but not always. The issue is that the code is running in IE in a limited-trust “sandbox” and doesn’t have enough permissions to use the Oracle client. The current security zone displayed is Intranet. In order to get these clients to work, you will have to tell the .NET Framework on each client that your assembly is trusted. Since it is under five clients you can probably get away with a manual fix.

    This probably won’t be exactly correct, but the right track anyway. Run Start/Control Panel/Administrative Tools/Microsoft .NET Framework 2.0 Configuration to open the configuration MMC snapin. Are you installing the control on the clients in the GAC? Once you open the MMC, browse to My Computer/Runtime Security Policy and click Increase Assembly Trust in the right-hand pane. Click Next on the first wizard page, and the second will ask for the assembly you want to trust. Unfortunately, you can’t point directly to the GAC, so you need another copy of the assembly just for the purpose of pointing to it once here. You’ll need to give it full trust. Another way you can configure .NET security is with the caspol.exe command-line tool, and you might be able to trust your entire website vs. the specific assembly. You’ll have to do a little experimentation to see what scope of trust works.

    I hope that helps. — Tom

  32. That was the ticket! I had actually gone through that exercise with the .net 1.1 wizard. For whatever reason, I didn’t think to do it for 2.0. In the 2.0 wizard, I was able to use the Adjust Zone Security wizard to grant Full Trust to the Local Intranet zone. And, like magic, no more errors!

    Thanks again for all your help, Mike.

  33. Does this require re-installation of .NET?? :(

    net.2.0 ;)

  34. Kral, I’m not sure what you are referencing. Nothing in my post requires reinstalling the Framework. Thanks, Tom

  35. Thanks for the suggestions :)

    I had a question regarding the “Process.PrivateMemorySize” etc under the Process class in System.Diagnostics. I tried several of these for a process (wanted to check the memory usage) which runs currently on my machine and compared that with that being displayed on the Windows Task Manager. None of them matched to what was there in the Task Manager.

    Which property in the Process class should i use to get the as far as possible accurate memory usage and which may turn out to be as the one in the task manager?

  36. we are in the process of creating a setup version for an ASP .Net application in .net 2.0 using visual studio 2005 under windows 2003 environment.

    the setup working fine and well. where as in case of windows 2003 OS when .net ver 1.1 co-exists with .net ver 2.0 then the IIS configures our application on by default to .Net ver 1.1 rather than .Net ver 2.0

    Resulting, user has to change to ver 2.0 in IIS (as given in the snapshot ) manually.

    Incase of system having only .net ver 2.0 installed there is no problem.

    Is there a way in web setup, where in we can make the application install on web server and get ver 2.0 selected in site setting in IIS.

    Thanks for your support!

  37. Lovneesh, I suggest creating a custom action to execute aspnet_regiis.exe. Here is a link related to creating a custom action: http://msdn2.microsoft.com/en-us/library/d9k65z2d(VS.80).aspx. Keep in mind that a 2.0 and 1.1 application cannot run in the same IIS application pool, so you may also need to create a new application pool and configure your virtual directory application to run under the new pool. The aspnet_regiis.exe command will be something like this: Aspnet_regiis.exe -s W3SVC/1/ROOT/SampleApp. You’ll have to determine the .NET Framework install path and the IIS internal path to the vdir to put all of the pieces together. I hope that helps. — Tom

  38. Hi Tom,

    We have several ASP.NET 1.1 applications hosted on the dev server. Recently We have develped a new app in ASP.NET 2.0 using Infragistics Controls(developed using Framework 1.1). At this time we are thinking of promoting the new app developed using ASP.Net 2.0 to production server. At present we only have ASP.NET 1.1 apps on production server.

    1. Does promoting the new App 2.0 to production affect the existing ASP.NET 1.1 applcations perfromance or stability?

    2. Will there be any difference in terms performance and stability between the ASP.NET 2.0 application developed using only 2.0 dlls and the one using some .NET 1.1 dlls ?

  39. Hi Sundar,

    1) the 1.1 and 2.0 applications will need to run in separate IIS application pools (on Windows Server 2003). They are separated into different processes and they won’t affect each other at all.

    2) There is a low chance of any difference, but it is possible that you could run into issues. An application runs either as 1.1 or 2.0, not both, so the 1.1 dlls will run under 2.0. For the vast majority of cases apps are forward compatible to 2.0, but not 100%. You would need to thoroughly test the app to ensure that there are no compatibility issues with the Infragistics controls. Otherwise, you can generally expect 2.0 apps to perform better than 1.1 apps.

    Thanks, Tom

  40. As long as I use separate app pools, if I install a 2.0 web application in a virtual folder under a 1.1 app’s virtual folder, is there anything I need to look out for? E.g.: /app_1_1/app_2_0? I know that when there’s a hierarchy of 2.0 apps then there are inheritance “features” with web.configs, but I wasn’t sure if that would occur with different frameworks.

  41. classic_craig, I do not recommend mixing 1.1 and 2.0 applications in a folder/subfolder tree. The web.configs can interact with each other in very frustrating ways. I’ve spent many a frustrating hour trying to make such structures work. So, that isn’t to say that it isn’t possible, but expect to do a lot of testing.

  42. Hi, I have a VB.NET program (built on v1.1) that is running on a Windows 2003 server. This machine has just the .Net Framework v2.0 installed (no v1.1).

    The customer reported that the program works fine, save for one problem: after completing execution, the window stays opened, instead of automatically closing.

    I’ve encountered this problem before, and I was able to fix it when I converted the program to v2.0 and set the value of the CheckForIllegalCrossThreadCalls property to FALSE (apparently, the program, being built on v1.1, is not thread-safe).

    However, I do not see the converted version of the program being deployed to the client any time soon, so I was wondering if you could provide any pointers as to how to fix the error while sticking with running it (v1.1) on a v2.0 machine.

    I apologize for the somewhat vague description of the problem, as I am not able to debug the program at the client’s machine.


  43. PGC, I can’t tell if you have identified that the issue goes away if the 1.1 app is actually running on 1.1 Framework vs. 2.0, but there is no _technical_ reason that 1.1 can’t be installed on the Windows 2003 Server. They may not want to, which is a different issue. You would just install Framework 1.1 and then put a <program>.exe.config next to your app to force it to use 1.1.

    Given what you termed as a fix on the 2.0 version of the app, I would suggest that you are likely only suppressing the error by disabling CheckForIllegalCrossThreadCalls. Threading issues are extremely hard to track down, so you might consider spending some more time trying to diagnose the core issue.

    Aside from forcing the app to run on 1.1 (if that matters) or modifying the code and redeploying, I do not think there is any way to actually fix the issue. You could try workarounds like starting the app with a Scheduled Task and giving it a timeout, so it can kill the process automatically after X hours, minutes.

    Thanks for reading, Tom

  44. Yes, the problem only came up when the app was run on the 2.0 framework. On 1.1, it works fine. I guess I have to check with the customer if they’re willing to have 1.1 installed on their machine as well.

    That’s right, setting CheckForIllegalCrossThreadCalls to False was just a workaround, as we were just trying to convert our objects to version 2.0 then. It seems like making v1.1 apps run on v2.0 is a hit-or-miss thing and it’s hard to pinpoint the errors, but are there things that I have to particularly look out for just to get me started on identifying the error?

    Thanks for the prompt response! The help is really appreciated.

  45. Hi PGC, in some cases 2.0 is just exposing the bad things that you could do in 1.1 that weren’t handled well. For instance, in 1.1 exceptions on non-UI threads were not handled particularly well, but that behavior was changed in 2.0. In your case, due to the particular setting that you are changing to fix/hide the issue, you may have code in a worker thread that is directly using a UI object, which is definitely off-limits. You must Invoke() back to the UI thread from the worker thread before touching any UI objects. Just a guess, but a common mistake.

    When you are actually running the 1.1 app (upgraded to 2.0) in the VS 2005/08 debugger, the new Managed Debugging Assistants (Debug/Exceptions…) can be helpful for finding subtle issues. In that same dialog, if you check “Thrown” for some of the other exception types, you may find exceptions occurring where you didn’t see them before. One caution being that _some_ are actually being handled, but the debugger will let you see them before the handler takes over.

    Thanks for reading, Tom

  46. Nice. Thanks for the tips. I’ll definitiely look into those. Thanks!

  47. Thank you so much, now my framework 1.1 and 2.0 in Windows Server 2003 is working at the same time.

  48. Hi Thomas,

    It’s a very nice article pointing to the solution directly. It saves lot of time.

    I have a quick question for you. We have project where we show the .Net Windows user control developed in 1.1 framework in Internet Explorer. The web application is deployed in webserver and the clients access it from their machines.

    If the client machine has both 1.1 and 2.0 frameworks installed, browser is trying to load the control using the framework 2.0 which is not acceptable in our case. If we create the config file ‘IEXPLORE.EXE.config’ with the ‘supportedRuntime’ parameters, it is working fine and loading the control with 1.1 framework.

    The problem here is, our client doesn’t accept this solution and doesn’t want to create this config file in all the client machines.

    Is there any other way where we can specify that the browser should use only 1.1 framework to load our dlls.

    Please help me out, if you know some way. Thanks in advance.

  49. Hi. I have an strange problem. I have a Windows Server with a little processor (1 GHz). Before the instalation of the .NET Framework 3.5 the server had some Web applications in classic ASP and ASP.NET 1.1. The server was fine. I created the pool aplication and puted an 2.0 framework web aplication here. This web site has become unpredictable. Sometimes the user see in his browser that no error is displayed, but an infinite load appear. The fist page of the site never load in the client. No errors reported in the server’s event viewer. I suspect that this is a machine’s resources problem, or may be I need an special configuration for the 2.0 framework application pool. What is the minimum hardware requirements to run the 3.5 framework? How I can configure the application pools in a limited CPU processor scenario?

  50. Very useful information.

    now i can run framework1.1 and 2.0 web applicagtion on same iis6 server.

    what i did

    1.I Created new application pool

    2.This application pool configurated on my application website (framework 1.1)

    3.I added following code on web.config


    <supportedRuntime version=”v1.1.4322″ />


    4. set aps.net version 1.1 in my web site.


    senthil Kumar