SSRS Error - There is an error in XML document (2, 2)

There is an error in XML document (2, 2)

I got this error when opening an SSRS project in Visual Studio. The solution. Upgrade SSDT.

Turns out my colleague had a higher version of SSRS component - if you go, within Visual Studio, Help > About it will give you the version number of Visual Studio then the individual component versions.