Bootstrapper Error 0x8013101b: Failed to create the managed bootstrapper application.

I developed Wix Burn based Managed bootstrapper, which required .Net Framework v4.0.xxx. It worked perfectly fine when I tried on Windows XP + Service Pack 2. That is, it initially launched .Net FW 4 Setup, which I packed in my Burn Package, and then launched my Boostrapper Installer.

But on Windows 7 without Service Pack 1, it was crashing with following log:

[0530:0B50][2014-01-21T11:39:50]i000: Loading managed bootstrapper application.

[0530:0B50][2014-01-21T11:39:51]e000: Error 0x8013101b: Failed to create the managed bootstrapper application.

[0530:0B50][2014-01-21T11:39:51]e000: Error 0x8013101b: Failed to create UX.

[0530:0B50][2014-01-21T11:39:51]e000: Error 0x8013101b: Failed to load UX.

[0530:0B50][2014-01-21T11:39:51]e000: Error 0x8013101b: Failed while running 

.

After some searching and digging, I finally able to solve it by editing BootstrapperCore.config file. Initially, it was:

< startup useLegacyV2RuntimeActivationPolicy="true" >
        < supportedRuntime version="v4.0" / >
        < supportedFramework version="v4\Client" / >
         < supportedRuntime version="v2.0.50727" / >

< /startup>
         

I removed < supportedRuntime version="v2.0.50727" / >. This causes bootstrapper to launch .Net FW 4.0 installation (Packed with as payload). 

Remember, on Windows 7 without SP1, there is .Net framework 3.5. So supportedRuntime version="v2.0.50727" causing the bootstrapper trying to use Net FW 2.0 or 3.5 and so failing, as my Bootstrapper is based on .Net FW 4.

Now, t updated the machine with .Net FW 4 and then launched my bootstrapper, and now working like charm.. :)