>Related question:
>I've seen cases where the classlib is definitely closed, in fact VFP is closed. However, copying a backup copy of the classlib into the test dir does not work. It says the file is in use. Now the production directory is open by other people, but not the test dir.

I would first be most suspicious that the other application with open files has this one open without you realizing it. Can you check which workstation has the file via your network monitor?


>Could it be because the classlib in both the test and production directory inherit from a parent classlib elsewhere? In other words, the production library has the parent library open, so the test library cannot be updated since it is based on the parent library which is open?

No. the OS has no concept f inheritance, this is implemented solely by VFP. And, when you open a library that holds the definition of a child class, it opens the parent class library to get the inherited PEMs. But it does NOT open the libraries containing other children, because It can't know about them- the parent class definition does not store a backlink to the all child classes.