Creating new Project results in '500 "Something went wrong"'

Summary

When I'm trying to create a new project i get a 500 - Something went wrong. In the webservice pod occurs following error message: Importing the project failed: 14:connections to all backends failing. debug_error_string:{"created":"@1676419614.897128451","description":"Failed to pick subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":3093,"referenced_errors":[{"created":"@1676419614.897127152","description":"connections to all backends failing","file":"src/core/lib/transport/error_utils.cc","file_line":163,"grpc_status":14}]}

Steps to reproduce

Fresh installed gitlab with helm - create new project

Versions

• Chart: Gitlab 15.8.1 / Chart 6.8.1
• Platform:
  • Self-hosted: K3s
• Kubernetes: (kubectl version)
  • Client: 1.26.1
  • Server: 1.24.8
• Helm: (helm version)
  • Client: 3.7.0

What does this mean? And where do I have to start searching? By the way: I'm using keycloak as a saml provider and my own certificates generated with an external cert-manager and an external issuer from letsencrypt(they are valid). Additionally im using Traefik as an Ingress Controller