[gentoo-user] Solved: KDE 5: Broken file protocol for KDE 4 apps caused by kwallet

["Jörg Schaible" <joerg.schaible@gmx.de>]

> Jörg Schaible wrote:
> 
>> Hi,
>> 
>> after the update to Plasma 5/KF5, I can no longer open (HTML) files from
>> my local disk with Konqueror. It claims it does no longer know the file
>> protocol. I get a similar error in Amarok when I try to apply a cover to
>> an album from the local disk. It seems all KDE4-based application are
>> affected.
>> 
>> Does anybody what's causing this behavior and know how to solve it?

Jörg Schaible wrote:

> Anyone? After upgrading a second machine to KDE/Plasma 5, I have the same
> behavior there. All KDE-4-based apps fail to interact with the file
> system. Using KMail I can no longer add any attachment to an email nor
> save an existing attachment to disk.

OK, finally I found the culprit. I knew that it had to be something in the 
configuration, because I did not had the problem with a new/unused account 
on the same machine.

After some hours of investigation (deleting and restoring files based on 
their modification time in the local configuration), I found out that the 
file protocol works if I remove the salt file of the KDE4 wallet.

Well, unfortunately this prevented KMail to access the mail servers, because 
the wallet was no longer accessible at all. But I could save attachments ;-)

In the end it turned out that the problem was caused by kwallet-pam. When I 
upgraded KDE 4 to 5 I also upgraded kwallet-pam directly. However, this 
prevents unfortunately the migration of the default wallet from KDE 4 to 5. 
This migration happens normally the first time when the default wallet is 
accessed and the user is asked for the wallet's password.

It seems that the PAM system will access the wallet way to early and the 
migration cannot be performed. I have no idea why this finally breaks the 
file protocol for KDE 4 apps, but this is what happens.

After deactivating the kwallet pam module (in /etc/sddm) and a reboot, the 
migration could be performed after the login and all apps behave properly. 
It is even possible to activate the PAM module again afterwards.

Hope this might help others. At least a big fat warning should be added to 
Gentoo's KDE 5 upgrade guide.

Cheers,
Jörg