Can't backup the registry

We are trying to do a full backup in order to migrate to a more powerful hardware, but it brokes when tries to backup the docker registry.

** Invoke gitlab:backup:create (first_time)
** Invoke gitlab_environment (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute gitlab_environment
** Execute gitlab:backup:create
** Invoke gitlab:backup:db:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:db:create
** Invoke gitlab:backup:repo:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:repo:create
** Invoke gitlab:backup:uploads:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:uploads:create
** Invoke gitlab:backup:builds:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:builds:create
** Invoke gitlab:backup:artifacts:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:artifacts:create
** Invoke gitlab:backup:pages:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:pages:create
** Invoke gitlab:backup:lfs:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:lfs:create
** Invoke gitlab:backup:registry:create (first_time)
** Invoke gitlab_environment
** Execute gitlab:backup:registry:create
rake aborted!
Backup::Error: Backup failed
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/files.rb:81:in `run_pipeline!'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/files.rb:37:in `dump'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:222:in `block (4 levels) in <top (required)>'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `block in execute'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `each'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `execute'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:214:in `block in invoke_with_call_chain'
/opt/gitlab/embedded/lib/ruby/2.6.0/monitor.rb:230:in `mon_synchronize'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:194:in `invoke_with_call_chain'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:183:in `invoke'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:17:in `block (3 levels) in <top (required)>'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `block in execute'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `each'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:273:in `execute'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:214:in `block in invoke_with_call_chain'
/opt/gitlab/embedded/lib/ruby/2.6.0/monitor.rb:230:in `mon_synchronize'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:194:in `invoke_with_call_chain'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/task.rb:183:in `invoke'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:160:in `invoke_task'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:116:in `block (2 levels) in top_level'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:116:in `each'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:116:in `block in top_level'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:125:in `run_with_threads'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:110:in `top_level'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:83:in `block in run'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:186:in `standard_exception_handling'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/rake/application.rb:80:in `run'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/exe/rake:27:in `<top (required)>'
/opt/gitlab/embedded/bin/rake:23:in `load'
/opt/gitlab/embedded/bin/rake:23:in `<top (required)>'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:74:in `load'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:74:in `kernel_load'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli/exec.rb:28:in `run'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli.rb:463:in `exec'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor.rb:387:in `dispatch'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli.rb:27:in `dispatch'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/vendor/thor/lib/thor/base.rb:466:in `start'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/cli.rb:18:in `start'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/exe/bundle:30:in `block in <top (required)>'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/bundler/friendly_errors.rb:124:in `with_friendly_errors'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/exe/bundle:22:in `<top (required)>'
/opt/gitlab/embedded/bin/bundle:23:in `load'
/opt/gitlab/embedded/bin/bundle:23:in `<main>'
Tasks: TOP => gitlab:backup:registry:create

Gitlab-check output, shows everything is OK:

# gitlab-rake gitlab:check SANITIZE=true
Checking GitLab subtasks ...

Checking GitLab Shell ...

GitLab Shell: ... GitLab Shell version >= 10.0.0 ? ... OK (10.0.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK

gitlab-shell self-check successful

Checking GitLab Shell ... Finished

Checking Gitaly ...

Gitaly: ... default ... OK

Checking Gitaly ... Finished

Checking Sidekiq ...

Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1

Checking Sidekiq ... Finished

Checking Incoming Email ...

Incoming Email: ... Reply by email is disabled in config/gitlab.yml

Checking Incoming Email ... Finished

Checking LDAP ...

LDAP: ... LDAP is disabled in config/gitlab.yml

Checking LDAP ... Finished

Checking GitLab App ...

Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
5/1 ... yes
<....>
17/317 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.22.0 ? ... yes (2.22.0)
Git user has default SSH configuration? ... yes
Active users: ... 9
Is authorized keys file accessible? ... yes

Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished

System INFO:

# gitlab-rake gitlab:env:info

System information
System:
Current User:   git
Using RVM:      no
Ruby Version:   2.6.3p62
Gem Version:    2.7.9
Bundler Version:1.17.3
Rake Version:   12.3.2
Redis Version:  3.2.12
Git Version:    2.22.0
Sidekiq Version:5.2.7
Go Version:     go1.13 linux/amd64

GitLab information
Version:        12.3.4
Revision:       f33961a3395
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     10.9
URL:            http://gitlab.ontnostromo
HTTP Clone URL: http://gitlab.ontnostromo/some-group/some-project.git
SSH Clone URL:  git@gitlab.ontnostromo:some-group/some-project.git
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers:

GitLab Shell
Version:        10.0.0
Repository storage paths:
- default:      /var/opt/gitlab/git-data/repositories
GitLab Shell path:              /opt/gitlab/embedded/service/gitlab-shell
Git:            /opt/gitlab/embedded/bin/git