Migration Zammad to new Server: uninitialized constant ActiveRecord


I would like to migrate Zammad with the Backup and Restore function from my old Debian Server to a new Ubuntu Server.

  • Used Zammad version old Server: 3.2
  • Used Zammad version new Server: 3.2
  • Used Zammad installation source: package
  • Used Zammad installation source: package
  • Operating system old Server: Debian (8.11),
  • Operating system new Server: Ubuntu (18.04.)
  • Browser + version: Firefox
  • Database old Server: MariaDB 10.1.43+maria-1~jessie
  • Database new Server: MariaDB 10.1.43-MariaDB

Expected behavior:

  • Login to Zammad

Actual behavior:

Zammad is runnig on the new System, but if i want to login i get the following message:

{"error":"uninitialized constant ActiveRecord::ConnectionAdapters::PostgreSQL::OID"}

Steps to reproduce the behavior:

  • Install Zammad
  • Edit the database.yml to the new database
  • Import the Backup on the new Server with zammad_restore.sh or an Mysql Import with the cli



is the adapter in database.yml set properly?

yes, i set the following attributes:

adapter: mysql2
database: zammad
pool: 50
timeout: 5000
encoding: utf8
username: zammad
password: xxx

Hi Florian,

I was have identical issue after migration in new server - I was the same OS, DB and Zammad version.
In my case clearing cache was resolve the issue:
zammad run rails r ‘Cache.clear’


1 Like

This helped me with a similar issue - in my case it was switching database providers from Postgres to MySQL. Thanks a million!

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