Installed wrong Debian Package while upgrading

Hello,

while upgrading my Gitlab EE instance from version 11.2.3-ee (aadca994) to the newest 11.2.5 I installed the wrong .deb Package (Stretch instead of Jessie). The installation failed with the error "LoadError: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version GLIBCXX_3.4.21' not found" When i then try to install the right package with dpkg -i, the installer fails with that error: Malformed configuration JSON file found at /opt/gitlab/embedded/nodes/servername.json. This usually happens when your last run of gitlab-ctl reconfigure didn't complete successfully. This file is used to check if any of the unsupported configurations are enabled, and hence require a working reconfigure before upgrading. Please run sudo gitlab-ctl reconfigure to fix it and try again.`

The run of gitlab-ctl reconfigure ends with this error: gitlab-ctl-result.txt

How can i fix my installation?

Thank you.