iTunes 10.5.1 (142) Match Error Message

I'm getting this, too. I wonder if it's due to having a fairly large library - iTunes installs on my other machines in the house have been able to do their synch/upload cycles just fine, but they typically only had a few albums, the machine that's failing is my primary media server.

According to: http://raptor.hk/itunes-error-codes-with-explanation/ , 4001 means "requiredFlagsDontMatch"... well, that's informative.

I do have the same issue now. I tried five times and all failed. Currently, I'm doing it again after logging out and back in. It's now in Step 1. The error always occurs a while after going into the Step 2. Are we the only ones having this? I first thought the server was overwhelmed.

There's also this, much larger thread on it: https://discussions.apple.com/thread/3349657?answerId=16743127022#16743127022

That thread presented a solution. Strange at it seems, this has worked for a lot of people: hold down the "option" key while you select "turn off iTunes Match", and then turn it back on.

Thanks, Babasyzygy. After I posted the comment of mine here, for some reason, I did these:

1. Press Command-J > Check iCloud Status checkbox.

2. Select one song in 'Music' > Right click the song > Click "Add to iCloud"

And it started the first step in the Match. And it went through the step 2 without the error! The process is now in the step 3, uploading songs. Weird, but this was the way the issue was resolved.

Try holding Option while turning iTunes Match off, then enable iTunes Match again.

It worked for others in this thread -> I got error message 4001 when trying to upload music to imatch

The "Add to iCloud" trick worked for me after trying everything else. Thanks!!!

Holding down the Option key as described resolved the issue for me!

That worked for me! Thanks so much for sharing that!

My itunes match is off, and I still get this error. I do not get option "add to icloud" from right-click menu, when clicking on a song.