Upgrade to Natty fails with "could not calculate upgrade" due to Sunbird

[Tanmoy]

I am attempting to upgrade from Maverick to Natty on a 64-bit system.

Here is my terminal output:

update-manager -d
extracting 'natty.tar.gz'
authenticate 'natty.tar.gz' against 'natty.tar.gz.gpg'
WARNING: Failed to read mirror file

At this point, "Computing changes" fails with the error message:
"Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade:
E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

This can be caused by:
* Upgrading to a pre-release version of Ubuntu
* Running the current pre-release version of Ubuntu
* Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug against the 'update-manager' package and include the files in /var/log/dist-upgrade/ in the bug report."

I have disabled all third party ppas in software sources. "main.log" and "apt.log" from /var/log/dist-upgrade are attached. "term.log" was empty.

[Jeremy (jeremyfrankly)]

I have the same problem on 32-bit

[Jean-Baptiste Lallement (jibel)]

Thanks for your report.

One of the problem is caused by sunbird which is not in the archive anymore. Can you try to remove it and retry the upgrade.
If it fails again, could you please attach the new log file /var/log/dist-upgrade/apt.log

Thanks.

@Jeremy, please file another report. many different causes can generate this error. Thanks.

[Sir Mix (dragonfly-hk)]

Same problem. Logs attached. Term.log is empty.

[Jean-Baptiste Lallement (jibel)]

@Sir Mix, your problem is different, please file a new report. Thanks.

[Tanmoy (tanmoylaskar)]

Wow.

Jean-Baptiste, how can I thank you enough? That fixed the problem. How did you figure it out?
Now, if only I can get the desktop-cube back :) I'll keep searching...

Thanks again!

[intelliboy (darshakthakore)]

I am having the exact same problem while upgrading from 10.10 64 bit to 11.04