I am trying to install .Net Framework 3.5 (required by many applications) on a brand new out of the box Surface Pro 3 running Windows 8.1 64bit.  When I attempt to install I get the following message.

The following feature couldn't be installed .NET Framework 3.5 (includes .NET 2.0 and 3.0) Windows couldn't find required files to complete the installation...........

Error Code 0x800F081F

I am connected to the Internet.  I have tried accessing the source files via an external HD containing Win 8.1 installation files.  Basically I have tried everything that I have found on the Internet with no luck.  It appears that the problem lies in the fact that Security update KB2966826 is installed on the unit and was so when it was delivered.  There appears to be no way to uninstall this update.  I have reset the Surface Pro back to factory defaults several times the most recent being 7/23.  Since the update came on the unit it is installed at every reset.  I am looking for help with uninstalling security update KB2966826.

Thank you

Hi MLPHRP,

We could run "wusa /uninstall /kb:2966826" to uninstall the update. In addition, the KB2966827 and KB2966828 may also be related.
It is not recommended to uninstall any security updates. Please install them again once you have installed the .net framework 3.5 successfully.
Here is a link for reference:
0x800F0906 and 0x800F081F Error Messages While Installing .NET Framework 3.5 in Windows 8/8.1
http://www.askvg.com/fix-0x800f0906-and-0x800f081f-error-messages-while-installing-net-framework-3-5-in-windows-8/
NOTE: This response contains a reference to a third party World Wide Web site. Microsoft is providing this information as a convenience to you. Microsoft does not control these sites and has not tested any software or information found on these sites.

Best regards

I ran the suggested wusa command at the admin command prompt and received the following message.

"Security update for Microsoft Windows (KB296626) is required by your computer and cannot be uninstalled". 

I have already tried the suggestion related to the link that you provided.  Any other suggestions would be appreciated.

Thank you

Hi MLPHRP,

I have tried to uninstall the KB successfully.

Please restart the machine and try to uninstall it again to have a check. If there is any antivirus software installed, please turn them off temporarily to have a check. 

If the issue persists, please run "dism /online /cleanup-image /restorehealth" or "sfc /scannow" to check the health of the system files. 

Best r

Thanks for the attempt.  I tried each item you suggested but still no luck. Both of the scans checked out.  Windows Defender was turned off.  The wusa command gave me the same message that I reported in my previous post.  This is becoming desperate.

Hi MLPHRP,

Please try to uninstall it in safe mode to have a check.

Best regards

Same result as before.  No success.

Hi MLPHRP,

I hope the following group policy will be useful.

Cant Install Microsoft .NET Framework 3.5 in Windows 8 and Later

http://www.askvg.com/fix-cant-install-microsoft-net-framework-3-5-in-windows-8-and-later/

Considering you have reset the machine, please ensure the machine has got all the updates and then have a try.

NOTE: This response contains a reference to a third party World Wide Web site. Microsoft is providing this information as a convenience to you. Microsoft does not control these sites and has not tested any software or information found on these sites.

Best r

The results were the same.  I am not able to install .net framework 3.5 without uninstalling KB2966826 and Microsoft will not allow me to uninstall it.  I have to think that Microsoft is aware of this problem as I am not the only one experiencing it.

Thanks

Hi MLPHRP,

Please install this KB 3005628 and then have a check.

Here is a link for reference:

Update for the .NET Framework 3.5 on Windows 8, Windows 8.1, Windows Server 2012, and Windows Server 2012 R2

https://support.microsoft.com/en-us/kb/3005628

Best regards

The results were the same as previous.  It seems that this patch is designed to remove KB2966828.  I ran KB3005628 even though KB2966828 was not installed on my Surface Pro 3.  My problem is that I am not able to uninstall KB2966826. 

Still very open to suggestions.

Thanks

Hello I am having this same exact issue. Have you gotten anything to work?

So far no luck at all.  You would think that Microsoft would have recognized this issue and published a fix.  If you come up with anything please post.  I will do the same.

Thanks