We ran into this issue a while back, and it turned out to be due to the fact that the symbolic links folder, Sage300Local, was not getting created on those workstations with the 40960 error.  We resolved the issue by installing programs locally to that folder.  Later, NLINDQ on this forum provided the following, better, solution:

We ran into this issue when upgrading to the 2019 version on a couple of workstations; for whatever reason the C:\sage300local folder wasn't created by the installer.  IMO, a better workaround than installing the folder locally is to manually create a symbolic link to the network folder.

From an elevated command prompt in the root of C:, run:

mklink /d Sage300local [path to sage programs]

This will create a symbolic link (NOT a shortcut) to the proper location and everything seems to work after that. Note that the link target must exist in the elevated environment for the command to succeed; if you're using mapped drives you may need to net use [DL]: \\uncpath-to-sage-filesbefore attempting to create the link.

That's probably it. I've had that issue before where the symlink was not being created and Sage300 throwing the same error. An alternative to creating a symlink, you could always update the ACCPAC registry key (in hklm/software/wow6432node) + environment variables to point directly to the sage300 server.

Good to know.  Thanks for that tip.

Good to know.  Thanks for that tip.