Missing partial wiki_extensions/_html_header

[Julian0815]

Hi,

I try to install the wiki plugin on redmine v4.0.7.stable
after copying the redmine_wiki_extensions directory to /usr/share/redmine/lib/plugins I restarted apache2.
Now it's impossible to use redmine (500 internal server error).

in /var/log/redmine/default/production.log there is an error message:
Started GET "/admin/plugins" for *** at 2021-09-18 14:51:53 +0200
Processing by AdminController#plugins as HTML
Current user: admin (id=1)
Rendering admin/plugins.html.erb within layouts/admin
Rendered admin/plugins.html.erb within layouts/admin (20.2ms)
Rendered admin/_menu.html.erb (4.6ms)
Rendering layouts/base.html.erb
Rendered layouts/base.html.erb (6.5ms)
Missing template, responding with 404: Missing partial wiki_extensions/_html_header with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby, :rsb]}. Searched in:

• "/usr/share/redmine/app/views"

Rendering common/error.html.erb within layouts/base
Rendered common/error.html.erb within layouts/base (0.5ms)
Completed 500 Internal Server Error in 52ms (ActiveRecord: 10.1ms)

ActionView::Template::Error (Missing partial wiki_extensions/_html_header with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby, :rsb]}. Searched in:

• "/usr/share/redmine/app/views"
  ):
  13: <%= stylesheet_link_tag 'rtl', :media => 'all' if l(:direction) == 'rtl' %>
  14: <%= javascript_heads %>
  15: <%= heads_for_theme %>
  16: <%= call_hook :view_layouts_base_html_head %>
  17:
  18: <%= yield :header_tags -%>
  19:

lib/redmine/hook/view_listener.rb:59:in block (2 levels) in render_on' lib/redmine/hook/view_listener.rb:57:in map'
lib/redmine/hook/view_listener.rb:57:in block in render_on' lib/redmine/hook.rb:61:in block (2 levels) in call_hook'
lib/redmine/hook.rb:61:in each' lib/redmine/hook.rb:61:in block in call_hook'
lib/redmine/hook.rb:58:in tap' lib/redmine/hook.rb:58:in call_hook'
lib/redmine/hook.rb:96:in call_hook' app/views/layouts/base.html.erb:16:in _app_views_layouts_base_html_erb__758180808239225622_47278818520200'
app/controllers/application_controller.rb:508:in block (2 levels) in render_error' app/controllers/application_controller.rb:506:in render_error'
app/controllers/application_controller.rb:494:in render_404' app/controllers/application_controller.rb:518:in missing_template'
Creating scope :system. Overwriting existing method Enumeration.system.
Creating scope :sorted. Overwriting existing method Group.sorted.
Creating scope :sorted. Overwriting existing method User.sorted.

What did I do wrong?

Regards
Julian