The project could not be prepared for publishing ... error (-49)

I have the same problem.

Tried this with no sucess:

https://discussions.apple.com/thread/3398814?answerId=16474163022#16474163022

Thanks,

Try turning off the iCloud Services altogether. Go to Apple Menu > System Preferences... > iCloud

Click on the Sign Out button. And just continue to click OK through all the messages pop-up until you get back to this login screen:

Reboot your Mac. Then check to back to see if iCloud is still logged out properly. If it is, then launch iMovie. And immediately try to Export your Project in the HD size that failed with Error -49 previously. There's been some recent speculation and testing of the PhotoStream service that might be the cause and/or Document/Data sharing that's the cause of this problem. Most of these messages were posted as recently as last night and yesterday Nov. 7, 2011

I am having exactly the same problem.

10.7.2, iMovie 9.0.4

13' MBP i7, 8GB RAM

I cannot create/export movies from ANY of my projects.

Signing out of iCloud did not fix my issue.

Thanks for the tip, though.

Thanks but did not worked for me....

I was able to complete the render at 720p.

The only change I made was sending the export to the shared volume on my Lion Server.

Perhaps if you have access to an external volume, you can try exporting to that.

read on another board this advice:

try switching-off the Local Mobile Backup

in Terminal copy/paste

sudo tmutil disablelocal

relaunch Mac, try again to export ...

please report here, if this solves your problem.

I had the same problem with iMovie '09 after installation of Mountain Lion.

Sharing to Media Browser did not solve my issue... however switching off time machine before starting the export did!

Just wanted to share this alternative solution.

Switching off Time Machine worked for me too. I'd tried about 10 times before to publish ... but no luck ... until I turned off TM. Thanks Somniu