Q: I too am getting the "Moving calendars to server account" pane when I open iCal

This works !!

OK, tried everything else, but it did not work. This did.

1) Deselect Calendar in iCloud and "delete".

2) Go to /Libraray/Calendar/ and deleted EVERYTHING!

3) REBOOT

4) Open Calendar, should be blank

5) Reenabled iCloud connect

6) Repopulating the Calendar took about 3 minutes, BUT it is working and the dreaded message is gone.

7) Bottom line, wipe Calendar clean in the Libraery of all old files and start over.

8) Nasty bug.

Melisolaris,

U are the BEST!!  Thank you so much.  Getting the "server account pane" error and not being able to access my calendar on the mac was driving me crazy.  Your method worked first time...and I am so thankful.  I was thinking I was going to be online with Apple support for hours and not be able to fix.  You are a "Godsend".  Thank you also for the very specific directions....made it so easy.  Best, angel

Thank you melisolaris  this helped me, and I now have my calenders back.

Thank you! This solved my problem!
I had to import each calendar afterwards (that I had backed up earlier), since for some reason all events didn't show. In Calendar: Archive - import - import...
  

I have followed this advice but in fact now I have an added problem - I'm stuck on "moving calendars to server account" - all my calendars have gone - although they are still on the cloud.  I keep having to force quit.  My calendar is now unchecked in system preferences as are reminders.  Any advice?

Thanks so much for this!!!!

Fixed it!! Thank you!

Thank you.  This did it for me after hours of trying to sync calendar to iphone and getting stuck at "moving calendars to server" message. 

After unchecking ical and reminders as stated in in Jim In Flagstaffs post, nothing happened till I did what the second post about logging out of ICloud suggested. it then worked!  Hooray for Jim in Flagstaff! They should have kept your city as the Capital of Arizona!