We have got emails from many users who are complaining about how they cannot run the .Net Framework 1.1 supported applications, as you may not know .NET Framework 1.1 is not supported on the Windows 8 or Windows Server 2012 operating system. In some cases, the .NET Framework 1.1 is specifically identified as required for an application to run. In those cases, you should contact your independent software vendor (ISV) to have the application upgraded to run on the .NET Framework 3.5 SP1 or later version.
But there are cases when the software version is old and you do not have the upgraded version of the software and for those users who tried installing old version as It is no longer supported. If you try to install the package, the following error message is displayed: "Setup cannot continue because this version of the .NET Framework is incompatible with a previously installed one."
Following are some methods to fix this issue
Install 3.5 Net Framework
For some users all those apps which need .Net Framework 1.1 to run can work properly either it’s a game or application with .net framework 3.5, you can optionally download .net 3.5 and install it but make sure you can turn off 4.0 framework and other versions if you have it apart from 3.5, so you have to turn off .net 4.0 and leave on 3.5
Another Way To Install .Net Framework 1.1
Download Microsoft .NET Framework 1.1 Redistributable Package (dotnetfx.exe). Make sure the setup file is saved as dotnetfx.exe. Download Microsoft .NET Framework 1.1 Service Pack 1 (NDP1.1sp1-KB867460-X86.exe). Make sure that the file is renamed and saved as dotnetfxsp1.exe, so that the rest of the steps can be followed easily. Move both installation files into the same directory (i.e. C:\DotNet)
Please Note: This method involves recompiling the .net framework 1.1 and then installing it .Net Framework 1.1 with slipstreamed/integrated Service Pack 1 by running netfx.msi which will created in the working folder after running the following commands.
run command prompt in admin mode and run the following command one by one.
dotnetfx.exe /c:"msiexec.exe /a netfx.msi TARGETDIR=C:\DotNet"
after it is installed.
msiexec.exe /a c:\DotNet\netfx.msi /p c:\DotNet\netfxsp.msp
We hope one of the above method will work for you to run any app or program, make sure to restart your PC after following any of the above methods.