cannot install NameError: uninitialized constant Redmine::Utils

[richman1000000]

Hi I'm trying to install this plugin in server and getting error

rake aborted!
NameError: uninitialized constant Redmine::Utils
/opt/redmine-4.1.1/lib/redmine/scm/adapters/abstract_adapter.rb:28:in <class:AbstractAdapter>' /opt/redmine-4.1.1/lib/redmine/scm/adapters/abstract_adapter.rb:27:in module:Adapters'
/opt/redmine-4.1.1/lib/redmine/scm/adapters/abstract_adapter.rb:25:in <module:Scm>' /opt/redmine-4.1.1/lib/redmine/scm/adapters/abstract_adapter.rb:24:in module:Redmine'
/opt/redmine-4.1.1/lib/redmine/scm/adapters/abstract_adapter.rb:23:in <top (required)>' /opt/redmine-4.1.1/lib/redmine/scm/adapters/subversion_adapter.rb:20:in require'
/opt/redmine-4.1.1/lib/redmine/scm/adapters/subversion_adapter.rb:20:in <top (required)>' /opt/redmine-4.1.1/lib/redmine/version.rb:3:in require'
/opt/redmine-4.1.1/lib/redmine/version.rb:3:in <top (required)>' /opt/redmine-4.1.1/plugins/redmine_ldap_sync/lib/tasks/testing.rake:27:in require'
/opt/redmine-4.1.1/plugins/redmine_ldap_sync/lib/tasks/testing.rake:27:in block (4 levels) in <top (required)>' /var/lib/gems/2.5.0/gems/rake-13.0.3/exe/rake:27:in <top (required)>'
Tasks: TOP => redmine:plugins:ldap_sync:test
(See full trace by running task with --trace)

[richman1000000]

turns out this command will not work.
rake redmine:plugins:ldap_sync:test