Quick update note: It looks like there are some users who’s also faced the same problem after upgrading to Mountain Lion. The fix described below works just the same with Mountain Lion!
So you’ve upgraded your Mac from Snow Leopard to the new roaring Lion. Once done, you browse around your Mac and is generally happy that everything remained working and all the data is still available as if nothing’s change except for the new features and functionality of Lion.
Then, you opened up iCal and noticed that your CalDAV-configured calendar isn’t working and is asking for you to reenter the password. You was sure nothing’s changed, but you go on and reenter the password anyway.
But the dialog box just keeps popping up!
Well, I too faced the same problem and thankfully, the fix is easy.
It seems that this is caused by some ‘corruption’ of sorts with the keychain that stores your password for the CalDAV configuration. All you have to the is just as the following:-
Firstly, you would need to know the CalDAV server address of the calendar configuration. If you know way it is, then go ahead and quit iCal.
If you don’t, then go to iCal Preferences (command+,) and go to the Accounts tab. Here, go to the Server Settings tab and copy down the Server Address entry.
iCal would only recognize any changes to the keychain entries when it restarts.
Once you’ve done that, next is to open up the Keychain Access app that can be found in Applications -> Utilities -> Keychain Access. Or, you can just use Spotlight (Command+Spacebar) and type in Keychain Access to start it.
What you need now is to search for the password entry of the CalDAV account. The easiest way to do so is to just search for it with by entering the CalDAV server’s address as you’ve noted from iCal’s settings.
Once you have those entries filtered down to the ones you are looking for, just delete them. If you have a few configurations that uses the same server address, such as if the email server and the CalDAV server is using the same server address, then you may choose to just delete off the ones that stores the CalDAV password. You can easily see this by clicking onto the Keychain entry and see the Where entry. You should see it starting with “http(s)://” and has “caldav” in the address. Email settings should start with “smtp://” or “imap://”.
If you are unsure, just delete all the entries and iCal and iMail would just prompt you again to reenter the password if it needs it.
Ok, once that’s done, just restart iCal. It would prompt you for the password again and this time, it would just work.
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