Q: OS X El Capitan Apple ID authentication problem

Thank you! This worked - making sure the /Users/Shared folder exists and setting the permissions on it finally helped me sign into iCloud successfully.

Here's a link to instructions for future answer seekers - http://www.cnet.com/news/itunes-crashing-with-access-privileges-error-in-10-6-7/

Before trying the above solution, I unsuccessfully tried the following -

1. Sign out of iCloud and try signing in again

2. Create a new account with admin privileges and try to sign into iCloud on the new account

3. Delete the iCloud account files under the user directory

I finally solved this after living with no apple id since upgrading to El Capitan in October. It was easy and it solved my problem, wish I'd thought of it sooner.

reboot, cmd+r, reinstall OS X

once it was done, I still had all my user data and apps, and apple id and itunes worked for the first time in months. Something about that initial El Capitan install back in October borked a file somewhere. Others have had luck with more esoteric solutions, but this easy fix did it for me.

I have the same error, but none of the listed solution apply to me. Both my App Store and iCloud can not login.

I delete the files in Users/Library/Accounts, which enable me to log into App Store.

I delete the files in Users/Library/Application Support/iCloud/Accounts, which enable me to log into iCloud.

Hope this solution can help someone.

Ok!

I don't if any of you already solved this problem, but I just found out something reaaaaally important about all this!!!

And I don't know if that is a direct solution for the problem you ppl are having, but for me was!

So, I open System Preferences>Users & Groups and for another reason I have to reconfigure my user ID.

To do that the dumb way (don't do it), you have to unlock Users & Groups panel, than right click on your acc to open "Advanced Options"

Then.. I saw it!!!! Under Apple ID definitions, there is an aliases definition, and mine had 2 entries: 1 stating my iCloud mail and another stating some else (a big name with lots of numbers in the last part). Ok, all I did was delete the second alias, and keep the first one (again, that was my iCloud user login, in my case an email).

If you are not sure if you can safely delete the second alias, copy it to a textedit file to save, and try.

I hope that solves the problem to everyone!!!

Cheers!

The answer to this is not reinstalling the OS, creating a shared folder, or anything like that. If you get the "This action could not be completed. Try Again" error the fix is relatively simple:

1) As one person stated, create a new Admin account. Tell it that you wan't to use your icloud password and associated apple ID (usually your email)  except when it comes time to type in that password there is an option not to use it and to make a separate one.

2) Make a new password.

3) After completing that it will try and prompt you to set up the icloud account. Decline this by skipping the step (or doing it later I can't remember what it says).

4) Once you are looking at the desktop go to sys pref. Log in to icloud. I simply checked the find my mac option and declined the rest. Login will be successful.

5) Then simply log out of that account via the apple finder (not the icloud accnt) , log back into your old Admin one and try re verifying the account option at the top of the icloud system preferences page. Voila!

Thanks! .. It worked

This worked...thanks Dookert!

All I had to do was download the latest version of iTunes from apple.com/itunes.  After installing, I was able to sign in to iTunes using my apple ID/password.  After doing that, I was then able to log in to iCloud from my mac and all is working.  Seems that installing and logging in to iTunes worked out the kinks.

This is clearly a bug but installing the latest iTunes then logging into the iTunes store cleared up the issue. Thanks.