Bug exists also with 1.66.139494.

Here is a easy recipe for reproduce this issue:

1. Have some mods installed to Arma3 Launcher, like:

@CBA_A3;@ASDG_JR;@Ace;@AllInArmaTerrainPackLite;@RHSAFRF;@RHSUSF;@vt5;@ace-comp-stuff

2. Have same mods installed to server (Windows, 1.48)

3. Connect server. Load missing, which uses those mods and verify you can go to the Multiplayer setup.

4. Exit game

5. Remove one mod from Arma3 launcher, like RHSUSF

6)Connect server, load missing which uses those mods and you are kicked out from server.

From Arma3 console log:
18:50:23 Game Port: 2302, Steam Query Port: 2303
19:34:40 <user> uses modified data file
19:34:40 Player <user> connecting.
19:34:42 Player <user> connected (id=).
19:34:56 Player <user> disconnected.
19:35:43 <user> uses modified data file
19:35:43 Player <user> connecting.
19:35:44 Player <user> connected (id=).
19:36:03 Mission co@ 8 RHS ACE AB Saattue Valtatiellä read from bank.
19:36:03 Player <user> disconnected.

Also, there is no error show to the Arma3 game, nor I cannot found any hint from Arma3Server.rpt.

Proposed procedure (like already in Arma2:OA)

1. Missing PBO / mod / file / reason for exit written to Arma3 console log with timestamp, player name and mission to be played.
2. Error message to be shown to end user with missing PBO / mod / file / reason for exit.

I doubt this is permission issue. I'm logged in to Windows using normal domain account (non-admin) and using that account I'm able to access files from the network share. I'm running Arma3 without admin accounts.

Test #1 - Following test was made
using command prompt:
net use i: \\storage-server\share\path
the I copied local disk contains of the Arma3profiles to that folder path
Next I changed the arma3 shortcut to have -profiles=i:\arma3profiles instead of -profiles=C:\users\<local_account>\arma3profiles

Started Arma3 from the icon without profile issues. I also checked that the files in that path were accessed as the timestamp was updated. (Files at C:\users\<local_account>\arma3profiles were not).

Then removing the I: -drive using
net use i: /delete

Test #2 - \\UNC -share
When I opened Windows explorer then expanded Libraries (from left) and clicked
properties on the documents (still at the left) I got Documents Properties window. It shows two Library locations. First is My Documents, which is pointed to \\storage-server\share\path.

https://www.dropbox.com/s/unt28c288h1khnx/documents-properties.jpg?dl=0

Next I changed the arma3 shortcut to have -profiles=\\storage-server\share\path\arma3profiles instead of -profiles=C:\users\<local_account>\arma3profiles

Same error message as in description.

--> Arma3 does not handle UNC paths, workaround is to store profile on local disk under c:\users\<local account>\somearma3directory and use -profile with the shortcut?

And just to clarify if I test
dir \\storage-server\share\path\arma3profiles
no access errors

mkdir \\storage-server\share\path\arma3profiles\test
directory is created, no access errors

rmdir \\storage-server\share\path\arma3profiles\test
directory is deleted, no access errors

This issue is still within 1.48 (Windows dedicated). When server is left on a multiplayer setup, in my server, it used about 17% CPU. Previous player signed off about more than 1 day ago.
CPU usage was dropped to a 3% after "#missions" was executed by server admin.

Wasn't there a timeout setting in ofp/arma/arma2 where it was possible for server to time out to mission selection if no other actions was selected in a pool for some time? If not, would this be possible to do after a last player is signed off?