Fixing "Please set registry key HKLM \ Software \ Microsoft \ .NETFramework \ InstallRoot to point to the .NET Framework install location" error on a 64-bit Windows PC

I recently got this error when trying to run/update WhatsApp's desktop client on my 64-bit Windows 8.1 PC:

.NET Framework Initialization Error

Please set registry key HKLM\Software\Microsoft\.NETFramework\InstallRoot to point to the .NET Framework install location

Trying to re-install several .Net Framework packages did not do the trick for me, so I kept on searching for solutions.

The .NET Framework Repair Tool provided by Microsoft did not work either. I even tried running the System File Checker tool (basically doing "sfc /scannow" in an elevated cmd) to no avail.

CCleaner showed a few registry errors related to the .NET Framework as well.

After trying numerous approaches to fix this, I found the following solution to be working in my case. I manually added the following string values in the Windows Registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework
InstallRoot=C:\Windows\Microsoft.NET\Framework\

AND

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework
InstallRoot=C:\Windows\Microsoft.NET\Framework64\

Adding just one of these string values did not work, so both are needed.

Here's how to do it, step by step:

1. Open regedit.exe by pressing Win+R, typing regedit.exe and then press Enter. More on the Windows Registry Editor here.

2. In the left pane, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework.

3. If the InstallRoot string is not present, simply right-click an empty space in the right pane and choose New > String Value. Name it InstallRoot.

4. Double-click the newly created InstallRoot string and fill in the Value data field with C:\Windows\Microsoft.NET\Framework\.

5. Repeat the process for the second location. In the left pane, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework.

6. If the InstallRoot string is not present, simply right-click an empty space in the right pane and choose New > String Value. Name it InstallRoot.

7. Double-click the newly created InstallRoot string and fill in the Value data field with C:\Windows\Microsoft.NET\Framework64\.

That's it, you can now close the Registry editor window. Things should work as expected now.

In my particular case, WhatsApp's desktop client resumed working normally afterwards.