I recently ran into a problem where I was getting the error:
Microsoft Visual Studio XAML UI Designer has stopped working
Microsoft Visual Studio XAML UI Designer has stopped working

I first noticed this problem when I was working on a existing WPF project (VS2012), so naturally, I created a brand-spanking-new project to see if it persisted.

It did.

The top of the stack trace for the new project was:

However, the stack trace for the existing project was different:

I was also getting this pop-up when I would first start Visual Studio (2012 & 2010).


Checking the ActivityLog.xml file here is what I got for my error:

Looks familiar, but…

…what do I get from this?

The only clue that I had was on line 4 of the trace.

Well it turns out that

The GetTempFileName method will raise an IOException if it is used to create more than 65535 files without deleting previous temporary files.


The thing is, my C:\Windows\Temp folder was empty!


Here is what MSDN failed to mention:
I needed to check my Users\<user>\AppData\Local\Temp folder! Once I cleared it I was good to go!

I hope this saves someone else from wasting some much appreciated coding time!

Happy Coding!