Yes, 6.2.28 controls the permissions differently with special BOINC limited user accounts for expanded security. Try uninstalling, reinstalling, and tick the All Users box. That will allow the BOINC Manager to connect to the core client.

I had the same problem when our Linux OS was upgraded. Linux automatically upgraded the Boinc.

The fix is to delete the newest version of Boinc and go back to the version that worked well. Yes, the older version of Boinc that previously worked will still work on your upgraded operating system.

I boxed two operating systems together -- Windows and Linux, both with Boinc, and the newest version of Boinc caused a lot of problems. It wouldn't work at all with the Linux upgrade, but did work with Win XP SP2 on our system. (I don't know what system you have).

Regardless of the type of computer system you have, or the operating system, if Boinc is not working properly, simply reverting to an older version of Boinc that did work, will fix the problem across the board for all our operating systems. There have been no problems with the older working version of Boinc.