Only Windows, Mac machines work fine.
1. Download and install the latest versions of perforce server and client
2. Create a workspace
3. Add your project to the server depot
4. Open Unity with that project
5. Go to "Edit -> Project Settings -> Editor"
6. Choose "Perforce" from Version Control option
==>
Editor will try to connect to the server then fails with "Version Control executable error"
Unity starts the PerforcePlugin.exe , it tries to connect then is killed with error.
The messages in p4plugin.log
Got config end = ''
Got config end = ''
Got config end = ''
....

The same behaviour for all the Unity versions I have (the oldest I tried is )
So, maybe our pluging cannot work with the new server