Unable to install or Launch Mixed reality portal after installing Windows update KB4090913 (OS Build 16299.251) in Windows 10 [Solved]

Right after the update KB4090913, Which was released on March 5,2018 most of the Windows 10 users reported that, they are unable to launch Mixed reality portal, it resulted in We couldn’t download Windows Mixed Reality error and when Some who tried to reinstall Mixed reality portal they got an error "We couldn’t download Windows Mixed Reality." 

If you are one of the person who received this error, then here is a quick guide that will fix the issue.

A quick look on what exactly happened..

Microsoft, had released this update, with some bug fix but it caused another bug, which is not a new one. Microsoft soon realized this error and removed the update from their Official sources to prevent many users from affecting,

How to fix..

Since, this is a known bug, you need to install another update to fix the problem

Symptom (As mentioned on Official Site)
After installing the March 5, 2018 update for Windows 10, KB4090913 (OS Build 16299.251), you may experience an error message when attempting to launch or install Windows Mixed Reality.
With Windows Mixed Reality already installed, when you attempt to launch the Mixed Reality Portal you may receive the error, "Something went wrong."
When installing or reinstalling Windows Mixed Reality you may receive an error, “We couldn’t download Windows Mixed Reality."

Here is how to fix Mixed reality portal after KB4090013 update..

1) Open Settings

2) Click on Update and security

3) Click Check for updates

4) Install KB4088776

5) Restart your PC.

That's it..

Alternatively, you can manually download kb4088776 from the below official site link.

Download link.