If you are just wanting to copy the folder to another server, I have done that many times.  No issue ever encountered with the 4.x versions.  Just reinstall the workstation.  If a version of Sage (client) already exists on the destination server, it should only need the MAS90 icon pointing to the folder.

Thanks Jeff and Wayne,
I have done that many times as well, however this time after copying the 4.05 MAS90 directory (it's actually a MAS 200 system) and running the parallel migration from 2017* I encountered some errors in some files. Apparently the only solution is to run rebuild utilities in 4.05, which I can't do because of this error (although, oddly enough, I can get into the Administrator Tools menu, just can't launch the Business Desktop):
Business Desktop
The following error has occurred.
Access violation at address 0047819 in module
'launch32.exe'. Read of address 00000320

I'll post the screenshot below. 

* I checked with Sage Support and normally I would go from 4.05 to 4.50.8 and then to 2021, but I was assured I could jump directly from 4.05 to 2017 - maybe that was bad advice.

Here's the message I'm getting, even after running wksetup in 4.05 on this 2019 server (and yes, I've tried various compatibility modes):

I have always heard the 4.0-4.4 upgrade path always goes through 4.5 PU8 first.

From 4.5 to 2017 should be the next step in the migration path to your final destination. 

From 4.5 to 2017 should be the next step in the migration path to your final destination.