Mchk command fails on step: mail_auth_dump

[Philippe12]

Dear All,

I just upgraded from plesk 11.5 to 12 and all my users are now unable to connect to their mailbox (pwd is not valid). After a few test, it appears that Mchk command fails on various steps

Errors occured in mail restore procedure
Some utilities have exited with errors:
/usr/lib64/plesk-9.0/remote_mail_restore/mail_auth_dump
/usr/lib64/plesk-9.0/remote_mail_restore/mail_imap_restore
/usr/lib64/plesk-9.0/remote_mail_restore/mail_outgoing_restore
/usr/lib64/plesk-9.0/remote_mail_restore/mail_transport_restore

Following http://kb.odin.com/en/121095
i checked that all mailboxes have a password:
SELECT CONCAT_WS('@',mail.mail_name,domains.name),accounts.password FROM domains,mail,accounts WHERE domains.id=mail.dom_id AND accounts.id=mail.account_id AND accounts.password='' ORDER BY domains.name ASC,mail.mail_name ASC; -> EMPTY SET

Checked whether there are accounts with passwords that cannot be decrypted
/usr/local/psa/admin/sbin/mail_auth_view | grep '$AES' -> RETURN NONE

Checked for mailboxes with an incorrect encryption
SELECT CONCAT_WS('@',mail.mail_name,domains.name),accounts.password FROM domains,mail,accounts WHERE domains.id=mail.dom_id AND accounts.id=mail.account_id AND accounts.type='sym' and accounts.password not like '%AES%' ORDER BY domains.name ASC,mail.mail_name ASC ; -> EMPTY SET

Checked that every mail account in the mail table has corresponding entry in the accounts table
select * from mail where account_id not in (select id from accounts); -> EMPTY SET

I'm currently unable to change passwords in control panel
Error message: Unable update mailbox: Mailbox password changing is not supported

Tried to run bootstrapper.sh -repair and got the following msg:

Some problems are found during reconfigure web-server configurations skipping broken domains(see log file: /var/log/plesk/install/plesk_12.0.18_repair.log)
and
PHP Fatal error: Call to a member function getScheme() on a non-object in /usr/local/psa/admin/plib/WebServerManager/Adapter/Apache.php on line 800

I'm stuck here so any help would be greatly appreciated...
Users are now playing darts with my photo but i'm still standing !

All my best,
Philippe