I need to move my iTunes Music folder from one external drive to another. Just drag and drop (135 GB)?

You should be able to alt/option start iTunes and return to the original library.

If that has become corrupt for some reason try Empty/corrupt iTunes library after upgrade/crash.

Given the starting position described it should have been as simple as copying the iTunes folder from one drive to the other and shift-starting iTunes to connect to it. One minor complication is that your media folder is called iTunes Music rather than iTunes Media, but that should not have had an impact on the playlists. Ah... Perhaps there are two files in the new folder, one called simply iTunes Library and another called iTunes Library.itl? Again the default name for the main iTunes library file has changed and while it doesn't cause a problem during iTunes updates, it can when switching libraries.

See Make a split library portable. Hopefully you can restore access to the original library, massage it into a more portable form, repeat those changes on the copied version, copy over the updated library files, and get the new clone working.

tt2

<<Preferences > Advanced will not tell iTunes where you media are located. It only tells iTunes where you want to start storing new media from that point on.>>

This is NOT true.

Going to Preferences: Advanced and selecting your media folder will most definitely tell iTunes where your media is located. I just used this very thing a few days ago when I renamed my media folder on an 8Tb external drive from iTunes to iTunes Media and it found my over 100,000 songs, 10,000 plus TV episodes, Apps and Movies and all my playlists stayed perfectly intact.

I have moved my iTunes media more times than I can count from one hard drive to another, to a different RAID drive, to a RAID backup and back again and I have never had any issues because I keep my Library file separate from my media which is on an external hard drive. As long as you tell iTunes where the media is located in Advanced: Preferences, it will find it and it will update the Library and .xml file to the media on the new hard drive while keeping all the playlists, play counts, whatever, intact.

I also copy the iTunes folder in Music on my Mac Mini over to my MacBook Pro for when I travel. I just plug in the external drive, start iTunes and have never, not once, had any issues. When I get home, I copy the folder back to my Mac Mini and all the changes made while I was away are all there.

The problem is when people keep their Library on an external drive when it should stay in the Music folder on the machine that is running iTunes. iTunes doesn't care where the media is located as long as it knows where to look.

Going to Preferences: Advanced and selecting your media folder will most definitely tell iTunes where your media is located. I just used this very thing a few days ago when I renamed my media folder on an 8Tb external drive from iTunes to iTunes Media and it found my over 100,000 songs, 10,000 plus TV episodes, Apps and Movies and all my playlists stayed perfectly intact.

This will work on a Mac because OS X automatically fixes any invalid reference within the same volume caused by moving or renaming folders. Changing the media folder path doesn't change which library file is accessed. In some cases if you move the media folder independently of iTunes, thereby potentially breaking the links from the library to the media, and give iTunes the new path to the media folder, it may manage to make sense of things. In some cases you may need to explicitly point iTunes to one of the relocated files and let it repair the others. What works reliably, on both OS X and Windows, is to keep the entire library in a portable format, in which case alt/option/shift-staring iTunes allows you to connect to a relocated library.

tt2

If you're going to start over use the option-start-iTunes method to create a new iTunes folder at the root of your chosen drive. Move all of your media inside the iTunes Media folder that will have been created inside that iTunes folder, then use File > Add Folder to Library to import the contents of the media folder. Clone the entire iTunes folder to a second drive as backup to the first.

tt2