Apple has announced a new update to iTunes through version 12.1, featuring new iTunes widgets for Notification Center in OS X Yosemite and performance improvement while syncing with iOS devices.
Besides, the latest update has a full 64-bit application on 64-bit edition of Windows 8, 7 and Vista along with other bug fixes.
But the newest version is reported to be creating trouble for jailbreakers. It seems iTunes 12.1 has broken restore to iOS 8.1.2 whereas for some users the TaiG jailbreak tool fails to detect iTunes, confirmed a redditor.
A potential fix for this issue is to downgrade iTunes 12.1 to the previous version 12.0.1.
In case you are looking for a guide for downgrading iTunes, head over to the following tutorial. You can use either of the methods depending on the OS version your machine is running.
How to downgrade iTunes 12.1 to 12.0.1 on Windows
Step-1: Uninstall iTunes 12.1 completely including all its remnants such as Apple Application Support, Apple Mobile Device Support and iCloud. Otherwise, the leftover might hinder the downgrade process
Step-2: Change the extension on your iTunes Library.itl file to iTunes Library.bak. This file can be found in
Step-3: Now reboot your Windows machine
Step-4: After a successful reboot, install iTunes 12.0.1
How to downgrade iTunes 12.1 to 12.0.1 on Mac
Step-1: Download Pacifist from Pacifist.com and install it
Step-2: Quit iTunes, remove all its traces using Activity Monitor
Step-3: Download iTunes 12.0.1 for OS X and mount it but don't install it
Step-4: Launch Pacifist, which you downloaded is earlier
Step-5: Click on Open package>> iTunes under Device in the left side bar.
Select Install iTunes and then Open in the bottom right corner
Step-6: Click on Contents of Install iTunes then select Install from the top bar. Follow the on screen instructions until installation begins
Step-7: After a few minutes, you should see a box saying Application already exists. Check Don't ask again for this installation box and click on Replace
Step-8: Wait for some time until the process is completed
You should now be running the older iTunes version 12.0.1. It's worth downgrading to iTunes 12.0.1 if you are a jailbreak lover.
[Source: Redmond Pie]