Can't enable .NET Environment in Windows 10 1903

For installing the latest CU try this:

Install this SSU: http://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4541338

Then install the CU: http://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4551762

As for upgrading to Version 1909, have you tried via the ISO? Just download the ISO file, mount it in Windows and run setup.exe to change from version 1903 to 1909. Because this is a cosmetic change to the Windows version number, it is not a full OS upgrade, but it does enable some things. This will also auto-install the latest Cumulative Update.

I actually did spend a lot of time yesterday testing. I installed version 1909 and was able to use my usual method to create the .NET fail. However, I could not fix it in any way that I tried. I even tried some methods that I had found online that involved replacing .MUM files in the C:\Windows\servicing\packages folder with files from the original ISO and then doing an in-place repair install (re-running setup.exe from install media for the same version that you have installed). But even a Windows Reset does not fix things. It has to be a clean-install, as what is needed for .NET to work after a Windows Reset simply isn't in the image anymore.

I have seen some explanations of why removing various packages makes them almost impossible to install. The mystery then is how in some cases .NET gets restored. An actual Windows OS build upgrade seems to work for anyone who needs to preserve their existing installed software, so upgrading to Insider Slow Ring build 19041.xxx should work.

I was able to use the following commands to remove or to install NetFx3. Removing the Capability made it impossible to install the latest .NET CU, but enabling the NetFx3~~~~ Capability enables the .NET CU to install.

DISM /Online /Remove-Capability /CapabilityName:NetFx3~~~~

DISM /Online /Add-Capability /CapabilityName: NetFx3~~~~

Here is the latest .NET CU:

http://catalog.update.microsoft.com/v7/site/Search.aspx?q=4537572

KB 4537572 Details:

https://support.microsoft.com/en-us/help/4537572

Hi Don,

That's okay. There's no need to test. I've already resolved to reinstall windows and bypass the problematic update (KB4495620). I noticed in my update history that the breaking update was literally the first update (June 5, 2019) and since then few updates have successfully completed. At this point I'm far more concerned about drivers and security fixes being out of date.

I also noticed, that since going through your fix steps that a few other items have mysteriously started reporting errors again. Skype for instance used to report errors upon loading into windows. Presumably that went away the same time I downloaded the update and I've not seen it since I enabled .NET 3.X yesterday.

The step I'm stuck on - after enabling .NET 3.X, I still can't complete an install of CUs. I tried installing KB4551762 for 1903 and even tried updating to 1909 but am unable to.

Again, thanks for all your efforts in this. It seemed to have helped a lot of people.

As you may have read here, I can replicate the issue and usually can resolve it. But I am not certain if this is exactly the same as when a device encounters this condition on its own.

I would be tempted, if possible, to replicate the steps that I used to disable .NET in the first place in my tests. Basically it was a thorough uninstall, using DISM or PowerShell commands. I also had tried using the new PowerShell Core versions, since they will install and run, even without .NET being functional.

I also found that using the Capability commands rather than the Add-Package commands is best. Often, if online, these will work without even referencing the source files from an ISO.

Also, build 19041.xxx is most likely only about 6-8 weeks away from becoming the public version of Windows 10, so it should not be a very extreme move to upgrade to that version at this point. It is being called the Windows 10 May 2020 Update.

I have not tested this issue in quite a while, so I could try replicating the issue with build 1903 again and see if the steps to resolve it are any different now.

Ah. I just tried installing 1909. It failed. Guess why? Missing .NET 3.5 compatibility. (Error 0x800f081f)

I also rebooted, just in case that was necessary after the .NET updates. In any case, both reboot and update to 1909 has failed after the fix above (my optional features list is still broken). I'm guessing a complete reinstall or opting in to windows insider and grabbing build 19041 are the only fixes?

Thanks for the valiant efforts, Don! I plan on reinstalling tomorrow or so, hopefully that will fix this .NET error.