Can't sync iPhone with iTunes 9.1 after update (Windows 7)

For what it's worth to anyone who's been struggling with this problem, by adding the sting - C:\Program Files (x86)\Common Files\Apple\Mobile Device Support;C:\Program Files (x86)\Common Files\Apple\Apple Application Support; - to the beginning of my path statement finally let me sync my playlists and podcasts today. I still got the "iTunes was unable to load dataclass information from Sync Services." error but the sync worked.

I'm disappointed that there has been absolutely no response from Apple on this. They should pay the folks who have submitted solutions here a consulting fee.

Still can't sync. Anyone have any new suggestions?

Hey all... I too have been having this same problem for weeks... After reading many threads in different forums I found my solution...

It may or may not work for you depending on your system. However this solution from posts from others have worked for these systems.

Windows Vista 32 & 64 bit versions, Windows 7, Those using Mobile Me and Office.

Here is what we were told to do and it worked. Just passing it on for others to attempt to see if it fixes your problems too.

Here is what we did.

You must copy TWO files from one folder to another.... It seems that these were placed in the wrong folder or they were left out of the last update.

I'm using VISTA so my files are in Program Files(x86) not the
regular Program Files folder... Make adjustments for the system you are using.

Go to > COMPUTER

C: drive
PROGRAM FILES(x86)
COMMON FILES
APPLE
APPLE APPLICATION SUPPORT +(ie: get the files from this location)+

Copy these two files... libxml2.dll and libtidy.dll

Then go PASTE them Here:

Go to > COMPUTER

C: drive
PROGRAM FILES(x86)
COMMON FILES
APPLE
MOBILE DEVICE SUPPORT +(Paste the two files in here)+

This helped all of us.... Maybe this will be your fix too.

Hope it helps...

LadyKJ

I tired that file swap already. Didn't work.

I tried the file copy method, copying all of the files from C:\Program Files (x86)\Common Files\Apple\Apple Application Support to C:\Program Files (x86)\Common Files\Apple\Mobile Device Support. After doing this I saw the check marks in iTunes on the Info tab for Contacts and Calendar, but it didn't work. A couple of new appointments in Outlook would not sync to my iPhone. I also made a change in one of my contacts, and this change didn't sync either.

Then I uninstalled all of the iTunes and QuickTime applications, according to knowledgebase article, HT1923, and also MobileMe. I then reinstalled the applications with the iTunes 9.1.0.79 install file that reinstalled everything except the MobileMe Control Panel. After installing iTunes, I again got the error that iTunes could not sync to the iPhone because syncing was disabled. I clicked "Yes" as always and got the second error message about provider data from Sync Services. I then reinstalled the MobileMe Control Panel, but got no error about a missing file. I have never gotten an error message about a missing file.

The new thing I now did was to go into System in Control Panel and into the Environment Variables and add the 2 folders:
C:\Program Files (x86)\Common Files\Apple\Apple Application Support
C:\Program Files (x86)\Common Files\Apple\Mobile Device Support

to the end of the path statement. You can try it by copying the following to your path statement:
;C:\Program Files (x86)\Common Files\Apple\Apple Application Support;C:\Program Files (x86)\Common Files\Apple\Mobile Device Support

The file copy method puts files in locations where they were not intended to be, but this method leaves everything ready for future updates. My sync with Outlook now works correctly again.

Still can't get mine to sync. Why is there no update to iTunes yet?

Just installed the latest iTunes version (9.1.1) and it seems to have solevd the sync issue/error messages. Glad this is finaly resolved.

Yes, 9.1.1 has no problem when upgrading from 9.0. Someone who has 9.1 installed with a problem might want to verify that 9.1.1 fixes it.

I had the same same problem syncing my iphone contacts with Windows Contacts using itunes 9.1, I run vista with all latest updates and Iphone os 3.1.1.

Eventually what I done was downgrade to itunes 9.0.3.

I'm running Windows Vista, Outlook 2007, and IE8. My Outlook files (contacts, calendar, notes), as well as my IE bookmarks don't sync to my iPhone 3Gs after installing iTunes 9.1 and then v9.1.1. All of my iTunes music, videos, photos, apps, etc. are syncing okay.

The only thing that v9.1.1 fixed was the error message that kept popping when I tried syncing my with my iPhone. After reading through this entire thread, I did try some of the "fixes" that worked for other, but none of them have worked for me. Now my only solution would be to go back to an earlier version of iTune, as some of the other posters have mentioned.

I'm just glad that I don't use my iPhone for my business, since it's been too unreliable. Apple needs to address this issue ASAP.

OS: window 7 64bit
iPhone 3GS MC model: 3.1.3 firmware
iTunes: 9.1.1 64bit

able to sync and all works well. However whatever you backup might have conflict and you have to decide phone or your outlook for cal and also for notes.

I have updated apple via email who is suppose to update me. Strangely who is getting paid i wonder.

Sorry if this information has already been stated, but I did not see it posted here.

It seems that past version 9.0.3, iTunes no longer is compliant with Microsoft's "Folder Redirection" for the "AppData" folder.

Normally a user’s “AppData” folder is located at

C:\Users\%username%\AppData\Roaming\

When folder redirection is applied, the path becomes closer to

\\server name\share name\%username%\Application Data\

As soon as I disable “Folder Redirection” for the “AppData” folder and the AppData files moved back to the local drive, iTunes did not show any more errors.

If you have a fast overclocked PC - Try running Prime 95 with 3 threads. I can sync every time I run this with 3 threads (2 will not work) and cannot otherwise sync except after repeated trys. I was OK until I installed iTunes above 9.0 Seems there is a timing loop Apple is using that was adjusted in iTunes 9.1+ I thought no one used a software (instead of hardware) timer. In any case if other things have not worked for you, you might give this a try.

THANK YOU so much! Worked like a charm. I've been chasing this for weeks.