XUnit.gui.exe – this assembly is built by a runtime newer than the currently…

So ran into this while using XUnit (For my new F# adventure) and I ran into this error when I tried to use the XUnit.gui.exe thing:

“This assembly is built by a runtime newer that the currently loaded runtime and cannot be loaded.”

Pretty straightforward in that I am creating projects in 4.0 and one can infer XUnit wasn’t ready for this. At first I was thinking, painful as that is, that XUnit can’t handle 4.0. To my relief, I found this post at:


Great… except it only talks about the xunit.console.exe.config and there wasn’t a xunit.gui.exe.config. Well in a moment of questionable brilliance, more like a slight moment of clarity, I decided to copy the xunit.console.exe.config and rename the copied file to “xunit.gui.exe.config” and it worked. Go figure.

This is a picture for the slighty less lazy:

And for those more lazy than that:

Here’s the xml in case you’re more lazy than I am.

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