Ubuntu 18.04 lts db error during installation

Infos:

  • Used Zammad version: 5.1.1
  • Used Zammad installation type: package
  • Operating system: Linux Ubuntu 18.04
  • Browser + version: not important

Expected behavior:

  • installation of zammad package without error

Actual behavior:

  • Error message while creating db
Traceback (most recent call last):
        59: from /opt/zammad/bin/rails:9:in `<main>'
        58: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        57: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        56: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands.rb:18:in `<main>'
        55: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command.rb:46:in `invoke'
        54: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command/base.rb:69:in `perform'
        53: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor.rb:392:in `dispatch'
        52: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/invocation.rb:127:in `invoke_command'
        51: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/command.rb:27:in `run'
        50: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `perform'
        49: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `eval'
        48: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `<main>'
        47: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:11:in `sync'
        46: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/relation/delegation.rb:88:in `each'
        45: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/relation/delegation.rb:88:in `each'
        44: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:12:in `block in sync'
        43: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/transactions.rb:212:in `transaction'
        42: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `transaction'
        41: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/transaction.rb:278:in `within_new_transaction'
        40: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
        39: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
        38: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
        37: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
        36: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
        35: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/transaction.rb:280:in `block in within_new_transaction'
        34: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `block in transaction'
        33: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:13:in `block (2 levels) in sync'
        32: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:62:in `sync_locale_from_po'
        31: from /opt/zammad/app/models/translation.rb:223:in `import'
        30: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:530:in `bulk_import'
        29: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:696:in `import_helper'
        28: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:761:in `import_with_validations'
        27: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `import_without_validations_or_callbacks'
        26: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `each_slice'
        25: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `each'
        24: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:824:in `block in import_without_validations_or_callbacks'
        23: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/adapters/postgresql_adapter.rb:29:in `insert_many'
        22: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:88:in `select_values'
        21: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:94:in `select_rows'
        20: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/query_cache.rb:107:in `select_all'
        19: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:70:in `select_all'
        18: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:489:in `select'
        17: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `exec_query'
        16: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:654:in `execute_and_clear'
        15: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:673:in `exec_no_cache'
        14: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:718:in `log'
        13: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
        12: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:727:in `block in log'
        11: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
        10: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
         9: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
         8: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
         7: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
         6: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:728:in `block (2 levels) in log'
         5: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:674:in `block in exec_no_cache'
         4: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
         3: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
         2: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
         1: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `block (2 levels) in exec_no_cache'
/opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `async_exec': ERROR:  insert or update on table "translations" violates foreign key constraint "fk_rails_d6e6d9635d" (PG::ForeignKeyViolation)
DETAIL:  Key (created_by_id)=(1) is not present in table "users".
        59: from /opt/zammad/bin/rails:9:in `<main>'
        58: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        57: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        56: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands.rb:18:in `<main>'
        55: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command.rb:46:in `invoke'
        54: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command/base.rb:69:in `perform'
        53: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor.rb:392:in `dispatch'
        52: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/invocation.rb:127:in `invoke_command'
        51: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/command.rb:27:in `run'
        50: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `perform'
        49: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `eval'
        48: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `<main>'
        47: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:11:in `sync'
        46: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/relation/delegation.rb:88:in `each'
        45: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/relation/delegation.rb:88:in `each'
        44: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:12:in `block in sync'
        43: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/transactions.rb:212:in `transaction'
        42: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `transaction'
        41: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/transaction.rb:278:in `within_new_transaction'
        40: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
        39: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
        38: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
        37: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
        36: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
        35: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/transaction.rb:280:in `block in within_new_transaction'
        34: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `block in transaction'
        33: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:13:in `block (2 levels) in sync'
        32: from /opt/zammad/app/models/translation/synchronizes_from_po.rb:62:in `sync_locale_from_po'
        31: from /opt/zammad/app/models/translation.rb:223:in `import'
        30: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:530:in `bulk_import'
        29: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:696:in `import_helper'
        28: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:761:in `import_with_validations'
        27: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `import_without_validations_or_callbacks'
        26: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `each_slice'
        25: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:820:in `each'
        24: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/import.rb:824:in `block in import_without_validations_or_callbacks'
        23: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-import-1.3.0/lib/activerecord-import/adapters/postgresql_adapter.rb:29:in `insert_many'
        22: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:88:in `select_values'
        21: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:94:in `select_rows'
        20: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/query_cache.rb:107:in `select_all'
        19: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:70:in `select_all'
        18: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract/database_statements.rb:489:in `select'
        17: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `exec_query'
        16: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:654:in `execute_and_clear'
        15: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:673:in `exec_no_cache'
        14: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:718:in `log'
        13: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
        12: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:727:in `block in log'
        11: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
        10: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
         9: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
         8: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
         7: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
         6: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/abstract_adapter.rb:728:in `block (2 levels) in log'
         5: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:674:in `block in exec_no_cache'
         4: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
         3: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
         2: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.4.8/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
         1: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `block (2 levels) in exec_no_cache'
/opt/zammad/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.4.8/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `async_exec': PG::ForeignKeyViolation: ERROR:  insert or update on table "translations" violates foreign key constraint "fk_rails_d6e6d9635d" (ActiveRecord::InvalidForeignKey)
DETAIL:  Key (created_by_id)=(1) is not present in table "users".
# Configuring Elasticsearch...
-- Nevermind, no es_url is set, leaving Elasticsearch untouched ...!
-- The above is all right if you don't want to use Elasticsearch (locally) - if this is not intended, consult https://docs.zammad.org !
Traceback (most recent call last):
        12: from /opt/zammad/bin/rails:9:in `<main>'
        11: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        10: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
         9: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands.rb:18:in `<main>'
         8: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command.rb:46:in `invoke'
         7: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/command/base.rb:69:in `perform'
         6: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor.rb:392:in `dispatch'
         5: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/invocation.rb:127:in `invoke_command'
         4: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/thor-1.2.1/lib/thor/command.rb:27:in `run'
         3: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `perform'
         2: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `eval'
         1: from /opt/zammad/vendor/bundle/ruby/2.7.0/gems/railties-6.0.4.8/lib/rails/commands/runner/runner_command.rb:45:in `<main>'
/opt/zammad/app/models/setting.rb:37:in `set': Can't find config setting 'es_url' (RuntimeError)
# Enforcing 0600 on database.yml ...

Steps to reproduce the behavior:

  • Fresh install Ubuntu 18.04 LTS
  • Create a postgres database cluster with locale en_US.utf8
  • Create user zammad with super user privileges
  • Create database zammad
  • Do all pre installation stuff mentioned in manual
  • Install zammad from package

Why are you creating database and user before hand? Is that happening on the same host?
What do you expect, how should Zammad know the credentials?

You’re not following the installation documentation at all. If you’re using package installation and want postgresql, simply follow the installation path:
https://docs.zammad.org/en/latest/install/package.html

It is an absolute zero brainer.

Thanks for your answer. You are totally right, with the correct environment it works as a non brainer.
In the meantime I found the problem. I previously installed Ubuntu 18.04 with a german charset. Therefore postgresql was also installed with a german charset. I removed the default instance and installed a new database instance with utf8 charset but still the db scripts didn’t work and were not able to create user and database.
Therefore I completely removed the virtual linux box and recreated it by then using Ubuntu 20.04 LTS. In this case I chose directly us english as installation locale and then zammad installed like a charm.
I think it is necessary that the linux box itself is an english one to have utf8 as a default for everything.