I have recently upgraded from Kubuntu 10.04.4-amd64 with KDE 4.4.5 to Kubuntu 12.04.1-amd64 with KDE 4.8.4.
The great part of the upgrade process was Ok, but the migration of previous email folders to the new kmail version apparently went wrong.
Now every time I start Kmail I get an error message saying that it "Could not create resource collection: Resourceid 4" and kmail shuts down.
By starting akonadiconsole and removing the Local Folders entry the error message stops and I can load Kmail, yet inside Kmail the Local Folder is empty (only an Outbox folder is visible) and none of my email messages is visible.
May old email messages are still located in .kde/share/apps/kmail/mail
I've noticed that in my home directory a new kmail2 folder has been created in .kde/share/apps/kmail2 and I've tried to move my old messages to the new new folder, but nothing changed.
I need help to restore proper Kmail functionality and have my old email messages back in place.

Thanks in advance

fresta

Try creating a new local folders resource (you can do that from the kmail account configuration) then use the File > Import procedure to import your old messages.

I've gone into Kmail Configuration and changed the path of "mail" and "Local folders" in order to make them both point to the previous maildir i.e.: .kde/share/apps/kmail/mail/ but nothing happens. I still get warning messages saying "Unknown resource".

Creating a new Local folder in kmail doesn't work as well.

Any other suggestion?

fresta

What kind of error do you get when creating new local folders?

No error. Nothing happens.

Can you try starting "akonadiconsole" and see whether your local folders resources are there and if they have any error?