.err file is always generated when posting

Problem

When I generate a program I get an *.err file even though I do not get any errors while posting

Make sure that the machine definition that you use for your process is loaded in Mastercam:
Go to Settings / Machine definition manager...
When the following prompt appears, select the checkmark:
Select the Edit control definition icon
Select Files, make sure the On fatal error is selected under Posting error file, save and click on check mark:
Mastercam will ask if you save the definition, select Yes.
On the machine definition manager window select the check mark again. Mastercam will ask if you to save the changes, select Yes again.
Finally Mastercam will ask if you want to replace the machine group, select Yes.