Issue Creating or migrating of subscription fails

[fliegerhermi]

This is the output from plesk migrator from Plesk Onyx to Ubuntu Obsidian

Failed to perform an action on subscription 'handschellenschlüssel.de': Failed to deploy subscription 'handschellenschlüssel.de'
Migration for that subscription is considered completely failed. No further actions are performed for it. Exception message: Migration tools tried to perform operation in 3 attempts.
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Attempt #1 failed with the following error:
Unable to create subscription 'handschellenschlüssel.de'.
Command execution failed on the local server with non-zero exit code.
command: /opt/psa/bin/subscription --create 'handschellenschl\xc3\xbcssel.de' -hosting true -hst_type phys -login hschluessel -passwd '' -ip 91.210.226.176 -do-not-apply-skeleton -notify false -owner floeffler -service_plan Unlimited -force -guid 65158457-9a6c-452a-b637-e9d46f04cbd4 -creation-date 2017-12-06 -ignore-nonexistent-options
exit code: 1
stdout:
stderr: [2020-04-05 14:30:37.678] ERR [util_exec] proc_close() failed ['/opt/psa/admin/bin/mailmng-outgoing' '--add-subscription' '--main-domain-name=xn--handschellenschlssel-4ec.de' '--out-limit=120'] with exit code [1]
An error occurred during domain creation: mailmng-outgoing failed: ERROR:__main__:UNIQUE constraint failed: domains.name


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Attempt #2 failed with the following error:
Unable to create subscription 'handschellenschlüssel.de'.
Subscription already exists on target server: most probably it was created at the previous attempt,
but migration tools are not sure if it was created correctly.
It is recommended to:
1) Resolve the original issue that caused subscription creation to fail,
delete subscription, and then run migration again.
OR
2) Ensure that created subscription is fine, or the original issue is minor,
then simply run migration for that subscription again.
----------------------------------------------------------------------------
Attempt #3 failed with the following error:
Unable to create subscription 'handschellenschlüssel.de'.
Subscription already exists on target server: most probably it was created at the previous attempt,
but migration tools are not sure if it was created correctly.
It is recommended to:
1) Resolve the original issue that caused subscription creation to fail,
delete subscription, and then run migration again.
OR
2) Ensure that created subscription is fine, or the original issue is minor,
then simply run migration for that subscription again.

The mailservice stays deactivated. When I try to activate it manually it fails with:

/usr/local/psa/bin/domain --update handschellenschlüssel.de -mail_service true

[2020-04-05 14:36:54.354] ERR [util_exec] proc_close() failed ['/opt/psa/admin/bin/mailmng-outgoing' '--add-subscription' '--main-domain-name=xn--handschellenschlssel-4ec.de' '--out-limit=120'] with exit code [1]

mailmng-outgoing failed: ERROR:__main__:UNIQUE constraint failed: domains.name

Any idea? I think it might be some problem with the IDN conversion.