Now KB5015814 won't install

Sorry I couldn't help you.

An easy search on the start bar for "Turn Windows features on or off" will get you to where you can turn off the ".Net Framework 3.5" it comes up as the first option. You just have click on the blue box with the minus sign that is next to the folder that has .NET framework 3.5 after it. When you click on that blue box it will turn white. Then you hit ok and if things go well it should remove (turn off) .NET framework 3.5 and probably make you restart your pc. After your pc comes back on you can just retry the update again. If you weren't able to turn off .Net Framework 3.5, then you have a more serious problem and at this time probably want to leave it alone. Since you seem to be a novice I don't recommend my other option of installing your OS over your OS. Like you said you'll probably have to wait for someone at MS to make the fix easy for you before it will get fixed.

You misunderstood. I am not a novice and have been trying everything since KB5014668 wouldn't install. I was making a comment that what you are saying is much too complicated for the average PC user and not necessarily the people responding here. If you've been following this thread, you'll note that this is NOT a Windows install failure as I as well as others have been able to download and install all other updates except these 2 KB's. This failure is unique to these cumulative updates. The 2 most common solutions that have worked so far is to do the in place upgrade or to turn off Malwarebytes if you have it. The later finally worked for me this morning and I was able to complete the install successfully.

Thanks for the information anyway... trying all these complex work arounds should not be necessary that's why I said the ultimate fix will have to come from Microsoft.

My .Net Framework 3.5 is already off. However, the 4.8 version is still on. I had this problem since May. Every other update went in fine except for monthly cumulative updates. If you go into my profile, you can see that I tried every solution except for reinstall OS. Also, I never had Malwarebytes so that's out. Been only using Windows Defender.

Are we really missing anything important if we skip these?

Same problem here. The 1 PC that didn't have MBAM installed was able to install the update no problem. The 2 PCs with MBAM though, big problems. PC1 showed the update installed in the history but still wanted to install it. It failed through Windows Update and manual installation. I reset Windows Update and rebooted. Had nothing but problems after that and now need to do a clean install as System Restore didn't help (even though it said it was sucessful) ans a Reset didn't fix things either.

PC2 I quit MBAM and turned off .Net Framework 3.5 (includes .Net 2.0 and 3.0) and the update took about 20 minutes but it's now installed.

As stated earlier, my computer had no malwarebytes ever. And somehow I still keep getting 0x8007000d after reaching installing 100% since May. I don’t know what is causing this.

Does anyone know if armory crate blocks this? Because I had it since I bought my pc and had no issues with updating. I’m starting to look for possible suspects. But the update installation still had the same result when I disable the service.