PartDB and Authentik

[pixbalance]

Is anybody using PartDB with Authenik for SSO and SAML? I tried to transfer the information from Keycloak to Authentik (https://docs.part-db.de/installation/saml_sso.html)

I have partdb, authentik and NGINX installed on unraid as docker.
My domain is https://partdb.mydomain.de, Login with local credentials in PartDB is working.

Current status:
When I click on the SSO login button on https://partdb.mydomain.de I end up in a error 500 page.
When I open Authentik https://auth.mydomain.de, log in and click on the App Icon for PartDB, login is working and a user is created.
Although I have added the user attributes email, lastName and firstName the user is created with a random number and no information used.
When I am logged in into PartDB and try to logout, I end up at error 500 page.

I have made the following settings:

SAML_ENABLED:
1

SAML_SP_ENTITY_ID:
https://partdb.mydomain.de
this value is from the provider metadata attribute "entityID"

SAML_IDP_ENTITY_ID:
https://partdb.mydomain.de
same as SAML_SP_ENTITY_ID

SAML_IDP_SINGLE_SIGN_ON_SERVICE:
https://partdb.mydomain.de/application/saml/partdb/sso/binding/post/
this value is from the provider metadata attribute SingleLogoutService -> Location with Binding Http-Post

SAML_IDP_SINGLE_LOGOUT_SERVICE:
https://partdb.mydomain.de/application/saml/partdb/slo/binding/post/
this value is from the provider metadata attribute SingleSignOnService -> Location with Binding Http-Post

SAML_IDP_X509_CERT:
....
this value is from the provider metadata attribute ds:X509Certificate

DEFAULT_URI:
https://partdb.mydomain.de/

SAML_ROLE_MAPPING:
{"admin": 1, "family": 5, "guest": 4, "*": 2}