I'm trying to convert an older mathcad file, however when I open mathcad the XMCD, MCD converter is greyed out and doesn't allow me to click.
you opened your discussion in the wrong section.
PTC eSupport Help is about how PTC technical support works.
I'll ask Toby to move this discussion for you.
what version was used to create older mathcad file (.xmcd) ? If you want to convert .xmcd to .mcdx (Mathcad Prime format) then:
To be able to convert file, both above mentioned version must be installed.
You need to have Mathcad 15 installed. You can get it here: http://www.ptc.com/engineering-math-software/mathcad/free-trial/thank-you
Point the license wizard at the license file you got for Prime.
Be aware that not everything in a Mathcad 15 file can be converted to Prime.