How do I fix "Unrecognized Guid format"

Question

I keep getting this error in VS 2013 if I click on the following file types:

1. *.cs
2. *.cshtml
3. *.config
4. *.asax
5. *.html

I just recently updated to Visual Studio 2013 Update 2 and fixed a compatibility issue to always run the "devenv.exe" as administrator because of UAC issues and running a service in windows 8.1. However; I can turn around and open this entire solution in SharpDevelop 4.4 and there are no issues. That would lead me to believe that the solution file wasn't the issue and it points to VS 2013 being the culprit on some level.

I have tried the following:

• devenv.exe /ResetSettings ( Did not work )
• Reset all settings to default without saving current settings ( Did not work )

Answer 1

It only worked for me when I unchecked all checkboxes and on the next screen at least one option was required so I checked "No I am done investigating the problem"

Note that this is based on other answers so first follow those procedures to open the "troubleshoot compatibility" screen for the devenv.exe

Answer 2

As stated in this Connect article, you have to run the troubleshooter again and validate that the fix worked. Additionaly, you should not check the box saying "it worked with older versions of windows", it would block some API required by VS.

Answer 3

We were able to fix this by doing the following

• Navigate to devenv.exe by right clicking Visual Studio from start, click properties, and select "Open File Location...".
• Right click on devenv.exe and select "Troubleshoot Compatibility".
• Click "Troubleshoot Program"
• Check "The program opens but doesn't display correctly"
• Click "Next"
• Click "Test the program"
• Confirm everything opens correctly
• Click "Next"
• Click "Yes, save these settings for this program"

Answer 4

I did an upgrade from Windows 8.1 to 10 recently, everything went smoothly. I can open my Visual Studio projects and debug them just fine until I run the Visual Studio 2013 Update 5 suddenly I get "Unrecorgnized GUID Format" error every time I open up any aspx/cs.

This is the steps I did to resolve the issue:

In Windows 10, you have to right-click devenv.exe and select "Troubleshoot compatibility". select "Troubleshoot program" and make sure that "it worked with older versions of windows" is unchecked.