VMWare Workstation step

[kinook]

It does appear that the variable f does not get disposed of (and its file handle closed) until after the action completes (not when f goes out of scope), so when vmrun is called later in the action, it isn't able to open the file. And the fix is to add the explicit close call as you did. Although that code shouldn't even get executed on the 2nd and subsequent invocations of the step (unless the .vmx file is getting replaced with a version that doesn't have that line).