I decided to store my mails in ~/Mail directory which seems not to be the standard place. kmail2 stores them temporary in .local/share/akonadi/file_db_data ! why ? - what a curious solution. Then after it cannot find the "Local directory" where it is expecting it, kmail2 prints an error message "Local directory - opening error, folder is missing" and probably requeues the mail, which means doubling it.
IMHO akonadi should store personal information and not the whole mailbox !
Any idea how to repair it now ?

thanks for the link to that FAQ. At least I was able to get KMail working again.

However, I still was not able to restore any of my old emails. I tried adding the local "old" KMail folder, but all I got was my old folder structure, without the emails.

Did they get lost in migration? Or is there a way to retrieve them?

If you restart Akonadi or right click and select "Refresh" then does that have any effect?

Is there any way to get back to kmail 1 - I mean the version which is not storing mails in akonadi ? I have over 5000 mail copies from doubling, which I cannot delete simply by editing a common mbox file and I think I have to give up.

KMail 2 should still be storing your email in the usual MBox / Maildir files. Akonadi and it's database is merely a *cache* of information, and *does not* act as the primary store of information.

In terms of going back to KMail 1, you would have to downgrade to KDE PIM 4.4, which your distribution may not allow.

One thing you could try is removing your configuration (moving all Akonadi and KMail configuration files) so as to get a fresh setup.

Restarting Akonadi Server did not achieve anything for me

Have you checked the article on Akonadi on KDE Userbase? It includes details on how to investigate failed migrations.

Thank you! I've been reading up about it but can't find anything to help me as currently Kmail is working...
As i mentioned before, my before - migration folderstructure is there, just not the emails, they must have gotten lostn in migration. I remember having error messages about it, but it's been a while and I don't recall what they said...

Hi,

I am using OCDC+Kubuntu, but I would guess that the issues described below are valid for other recent Linux distributions as well.

With a recent upgrade from Kubuntu 11.04 to 11.10, KDE was also upgraded to 4.7, and kmail changed from kmail1 to kmail2. The latter upgrade proved very disruptive for me, but I managed in the end.

So here are my experiences, solutions and work arounds.

Prior to KDE 4.7, you might get away with a broken akonadi configuration, but this broken akonadi configuration will hit you badly, when trying to migrate from kmail1 to kmail2. So you better open KDE menu, type akonadi into the search window, click on akonadi configuration, change to the tab "server configuration" and click on the "test" button. Then work on the problems that are reported there. In my case, I needed to install "mysql", which was required, but not really flagged as a prerequisite to akonadi.

If you then click on the kmail icon, it will start a migration utility. If your akonadi runs smoothly, the migration utility might complete without errors. If akonadi doesn't run, you get all sorts of strange errors, but no hint that akonadi might be missing or broken.

Even if the migration utility completes without errors, I found that my mails were not migrated properly. In fact, they were not migrated at all. After some contemplation I decided to purge all migrated kmail files and set up kmail from scratch. Then I used kmail->File->Import messages to import my old Kmail1 folders.

Importing messages went fairly smoothly, but I had to import in chunks of up to 9000 messages. Otherwise I would run out of memory and paging space. I first thought, the import utility had a memory leak, but when the importing completed, apparently all allocated memory and paging space was freed properly.

Finally, I used fetchnotes to have my Lotus Notes mails delivered to /var/spool/mail/<my_userid> and kmail1 would get it from there. Unfortunately, kmail2 does not work well with mbox type mail files. Searching with Google for these problems, I got the impression that these problems are there to stay - at least for some time. So I reconfigured procmail to have fetchnotes deliver to a mail directory - and this works very smoothly with kmail2. The details of this are in the comment to the following bug report https://bugs.kde.org/show_bug.cgi?id=287394 .

Have fun ! Christoph

The importing issue should be fixed in KDE 4.8 as far as I am aware. This is caused by the Nepomuk search indexer loading data faster than Nepomuk can index it.

While upgrading openSuse from 11.x to 12.1 kmail migration failed.
After a lot of (half-)failed migration trial an errors I found out:
there is a menu option to import messages.
File/Import messages
choose: import maildirectories and mailfolders of kmail
and select de mailfolder p.e. inbox, ( not de underlying cur directory)
p.e. .kde4/share/apps/kmail/mail/inbox
check also for hidden directories. One of my mailfolders started with a dot.
N.B. Translation might be wrong, I use dutch version.

Thanks a lot sofsaf!! FINALLY I'm about to recover my 10000 missing emails (only slightly slows down my computer.. oh well..) why didnt I have tht Idea? I only "included" the folder into my new kmail instead of importing it.. Solution found! Thanks a lot!

Thanks, sofsa. It worked for me yoo.