I just updated TeXstudio from 3.0.4 to 3.1.2, and uninstalled all the previous versions.
But now, when I try to compile my already saved files on this new version, I get the following error:
latexmk.exe: The script engine could not be found. latexmk.exe: Data: scriptEngine="perl.exe", scriptName="latexmk"
The internal PDF viewer shows the previous version of my file, complied. But it doesn't update to any changes I make to the code, and shows the above error.
Note that I already have MikTeX 2.9 installed.