I have tried everything! NOTHING WORKS!
Solution 1: Log your Apple ID out of iTunes, and then log back in. Authorize both iTunes accounts.
Solution 2: Delete the iPhone app that has been downloaded from different Apple account (account used for building app or downloading app)
Solution 3 : If you purchasing apps with 2 unique Apple/iTunes IDs
First de-authorize and signed out of all iTunes on all your Mac computers.
Log out of iTunes on iOS devices.
Now sign in to iTunes on 1 Mac and 1 iPhone with main iTunes login.
Authorize Mac with main iTunes account login.
Then authorize for any other Apple accounts you may have.
Finally sync Device.
Solution 4:Instead of syncing just make some changes in any videos or photos and press Apply.
That’s all. iTunes will sync normally. Don’t press sync.
Solution 5: Tick the check box”Manually manage Music & Videos”.
Then click Apply, and sync button. ( it will return to usual authorisation error. don’t worry.)
Again unchecked the box for manually manage music, click apply and sync.
Solution 6: De-authorize your computer and uninstall iTunes
Clean your computer with CCleaner.
Reinstall new version of iTunes and authorize your computer again.
Solution 7:
Open iTunes on the computer
From the menu bar select Account > Authorizations > Authorize This Computer
Enter password for your Apple ID, done.
PLEASE HELP! I DON'T KNOW WHAT TO DO ANYMORE! =(
Solution 1: Log your Apple ID out of iTunes, and then log back in. Authorize both iTunes accounts.
Solution 2: Delete the iPhone app that has been downloaded from different Apple account (account used for building app or downloading app)
Solution 3 : If you purchasing apps with 2 unique Apple/iTunes IDs
First de-authorize and signed out of all iTunes on all your Mac computers.
Log out of iTunes on iOS devices.
Now sign in to iTunes on 1 Mac and 1 iPhone with main iTunes login.
Authorize Mac with main iTunes account login.
Then authorize for any other Apple accounts you may have.
Finally sync Device.
Solution 4:Instead of syncing just make some changes in any videos or photos and press Apply.
That’s all. iTunes will sync normally. Don’t press sync.
Solution 5: Tick the check box”Manually manage Music & Videos”.
Then click Apply, and sync button. ( it will return to usual authorisation error. don’t worry.)
Again unchecked the box for manually manage music, click apply and sync.
Solution 6: De-authorize your computer and uninstall iTunes
Clean your computer with CCleaner.
Reinstall new version of iTunes and authorize your computer again.
Solution 7:
Open iTunes on the computer
From the menu bar select Account > Authorizations > Authorize This Computer
Enter password for your Apple ID, done.
PLEASE HELP! I DON'T KNOW WHAT TO DO ANYMORE! =(