Please sign in again. iTunes Match has encountered an error.

Yup. Updated everything. Just upgraded to lion yesterday, as well.

It's still doing "the thing". Guess they'll fix it eventually.

I updated to the latest iTunes version yesterday, and I still have the same problem. Match doesn't work, and the Cloud icon just continuously looks as though its trying to connect unless I sign out, sign in, and then re-add my computer to Match.

A few more details: Windows 7, no other streaming software (like Audio Galaxy) used, but I do have AVG. I also have a fairly decent sized mp3 library (over 14,000). Maybe the size of the library is the problem?

I installed the latest iTunes to my iMac running the latest Lion and still have the same problem. It keeps asking me to sign in again.

I fixed the problem. I uninstalled the latest version of iTunes (you have to right click on the program icon to get info, then change the permissions to "read and write" for all users to delete it)

I then made sure safari accepted cookies from iTunes, then reinstalled it (iTunes). Deleting it should prompt a clean install. Not really sure why they try to prevent people from deleting it in the first place, actually...

Everything started working at that point. Hopefully, it's not a fluke and it should work for everyone.

HAPPY HOLIDAYS!

Finally i fixed this problem by enabling Cookies in the Safari Settings :-)

I have fixed this at last. The problem seems to be some association between your Mac User account and iTunes. The fix (but not a good one) is to create a new user account on your mac and migrate everything to it. However, before you do this I suggest you just move a small number of tunes and Match using the small iTunes database.

Before doing this I tried deleting preferences etc. but nothing worked, then I tried another Mac I have and lo and behold it was working. I could access my iTunes account again through iTunes. AND Match worked.

Whilst this does work it is a real pain migrating music to the new account. But I had already done some work here migrating my classical collection which was huge and unlikely to have much success with Match anyway.

I haven't attempted to migrate the rest of my account as there are apparently 'permission' issues and the articles I've seen mention Utilities disk which you don't have with Lion.

So to add to the list - ME TOO. I am in Australia and just turned on the imatch service which became available this week. I am running itunes 10.5.2.11

It uploaded two thirds of my music then completely froze my Win 7x64 system (first program to ever do that.) Fully locked up - not even mouse movement. After system reboot them got the unpleasant news about itunes has encountered an error and please log out then log in. When I was then forced to Add Computer to do that it said my library was in use by another computer. I assumed it was this computer so said OK then it went on uploading the remaining songs. However the little cloud icon is now not against most of my songs which is frustrating. Even ones I had purchased via iTunes - about half have the symbol so it looks as if the imatch reconciliation process has gone wrong. BTW - I am not running any other music streaming service. I am running Norton AV 360.

C'mon Apple - itunes is close to the most hateful software ever released by you and has been flaky for years - please do try and work hard on resolving this. I really want to recommend the imatch service to my friends but cannot do so with confidence as yet.

And one more blast: this kind of useless error message is shades of the very early old Microsoft days: "Abort, Retry, Cancel" (when all options lead to a crash) that your old adverts made such fun about. Shame!

Me too, USA. Same as other posters, request to sign in again, and then request to add (same) computer.

And I have tons of non-Apple-purchased music in iTunes (ie my entire CD collection) so I am VERY nervous about any "fix" that involves removing iTunes.

Color me unhappy with Apple just now.

What??? That actually worked! Thanks!

(enable cookies in safari)

I'm having the same problem. Driving me crazy!

Okay, I got mine working, I think...no more lightning bolt through my iTunes Match icon on the Music folder (under library), and now I can update my Match library without issue. Now, I'm not sure exactly what step made it work but, most of all, for Windows 7 users, run iTunes with elevated privileges (which I think is the real trick):

1. Launch iTunes as an admin (right click on your iTunes icon and click "Run as administrator."
2. When iTunes loads, sign out, then sign back in.a) At this point, upon signing back in, my Match icon was gone from the Music folder, and it was looking for me to turn on Match again.
3. De-authorize the computer, then authorize again.
4. Now turn Match back on (the process seems like a quick check, and did not take as long as the first Match scan).
5. After iTunes Match is complete again, I was able to close iTunes open again with "Run as administrator," and my match was all good.
6. Close iTunes and reopen without "Run as administrator" and it's still good, updates Match with no issues.

Now, you might be able to skip 5 and just run without elevated privileges, but I figured just in case iTunes needed to write to a protected folder one last time upon launch. Hope this helps any Windows users out there, not sure if the Mac OS users having issues have something similar to elevated permissions when running an app, but I would try that.

yes, thank you! the annoying message is gone.... 🙂

Thanks to the previous post who noted the need for cookies to be enabled in Safari, that's all I changed on my imac and the problem stopped.

Sadly no solution posted here has solved the problem for me. I've deauthorized, reauthorized, logged again, etc, etc, and nothing.

It's really an annoying problem! Please Apple get it right!!!

This worked for me on my Windows 7 system. Great solution. Thanks!