Error trying to configure SMTP

I’m trying to configure gitlab to use my smtp server following the doc:
https://docs.gitlab.com/omnibus/settings/smtp.html#mandrill

But I got an error when I try to run gitlab-ctl reconfigure:

ERROR: Encountered unsupported config key ‘smtp’ in /etc/gitlab/gitlab.rb.

I’m using gitlab 10.5.3-ee

Here is the full log:

gitlab-ctl reconfigure
Starting Chef Client, version 12.21.31
resolving cookbooks for run list: [“gitlab-ee”]
Synchronizing Cookbooks:

  • gitlab-ee (0.0.1)
  • package (0.1.0)
  • gitlab (0.0.1)
  • consul (0.0.0)
  • repmgr (0.1.0)
  • runit (0.14.2)
  • letsencrypt (0.1.0)
  • postgresql (0.1.0)
  • registry (0.1.0)
  • gitaly (0.1.0)
  • nginx (0.1.0)
  • mattermost (0.1.0)
  • acme (3.1.0)
  • compat_resource (12.19.0)
    Installing Cookbook Gems:
    Compiling Cookbooks…

================================================================================
ERROR: Encountered unsupported config key ‘smtp’ in /etc/gitlab/gitlab.rb.

================================================================================
Recipe Compile Error in /opt/gitlab/embedded/cookbooks/cache/cookbooks/gitlab-ee/recipes/default.rb

NoMethodError

undefined method `mandrillapp’ for nil:NilClass

Cookbook Trace:

/opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/helpers/settings_helper.rb:100:in block in from_file' /opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/config_mash.rb:28:in auto_vivify’
/opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/helpers/settings_helper.rb:100:in from_file' /opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/helpers/settings_helper.rb:100:in block in from_file’
/opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/config_mash.rb:28:in auto_vivify' /opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/helpers/settings_helper.rb:100:in from_file’
/opt/gitlab/embedded/cookbooks/cache/cookbooks/gitlab/recipes/config.rb:23:in from_file' /opt/gitlab/embedded/cookbooks/cache/cookbooks/gitlab/recipes/default.rb:26:in from_file’
/opt/gitlab/embedded/cookbooks/cache/cookbooks/gitlab-ee/recipes/default.rb:20:in `from_file’

Relevant File Content:

/opt/gitlab/embedded/cookbooks/cache/cookbooks/package/libraries/helpers/settings_helper.rb:

93: def ee_attribute(name, **config)
94: config = { ee: true }.merge(config)
95: attribute(name, **config)
96: end
97:
98: def from_file(_file_path)
99: # Allow auto mash creation during from_file call
100>> Gitlab::ConfigMash.auto_vivify { super }
101: end
102:
103: def method_missing(method_name, *arguments) # rubocop:disable Style/MethodMissing
104: # Give better message for NilClass errors
105: # If there are no arguements passed, this is a ‘GET’ call, and if
106: # there is no matching key in the configuration, then it has not been set (not even to nil)
107: # and we will output a nicer error above the exception
108: if arguments.length.zero? && !configuration.key?(method_name)
109: breaktxt = ‘=’ * 80

System Info:

chef_version=12.21.31
platform=ubuntu
platform_version=16.04
ruby=ruby 2.3.6p384 (2017-12-14 revision 61254) [x86_64-linux]
program_name=chef-client worker: ppid=28222;start=17:51:02;
executable=/opt/gitlab/embedded/bin/chef-client

Running handlers:
Running handlers complete
Chef Client failed. 0 resources updated in 03 seconds
There was an error running gitlab-ctl reconfigure:

undefined method `mandrillapp’ for nil:NilClass