Maintenance-Plugin and Redmine 4.2

[MichaGeh]

Hi,
my configuration:
Environment:
Redmine version 4.2.3.stable
Ruby version 2.6.9-p207 (2021-11-24) [x64-mingw32]
Rails version 5.2.6
Environment production
Database adapter Mysql2
Mailer queue ActiveJob::QueueAdapters::AsyncAdapter
Mailer delivery smtp
SCM:
Subversion 1.9.2
Git 2.34.0
Filesystem
Redmine plugins:
easy_gantt 1.13
localizable 0.4.0
redmine_agile 1.6.2
redmine_base_deface 1.5.3
redmine_checklists 3.1.20
redmine_impersonate 2.0.0
redmine_issue_dynamic_edit 0.8.1
redmine_maintenance_mode 2.2.0
redmine_serial_number_field 3.0.0
redmine_smile_togglesidebar 1.0.7
redmine_xlsx_format_issue_exporter 0.1.6

i want to configure the maintenance-plugin, but i have gotten this error:

`Started GET "/settings/plugin/redmine_maintenance_mode" for 127.0.0.1 at 2022-01-27 17:24:26 +0100
Processing by SettingsController#plugin as HTML
Parameters: {"id"=>"redmine_maintenance_mode"}
Current user: root
Rendering settings/plugin.html.erb within layouts/admin
Rendered plugins/redmine_maintenance_mode/app/views/settings/_redmine_maintenance_mode_settings.html.erb (7.1ms)
Rendered settings/plugin.html.erb within layouts/admin (12.0ms)
Completed 500 Internal Server Error in 29ms (ActiveRecord: 5.0ms)

ActionView::Template::Error (incompatible character encodings: UTF-8 and CP850):
39: <%= l(:setting_time_format) >: <=Time.new.strftime("%Y-%m-%d H:%M")>
40:

41:

42: <%= l(:maintenance_mode_server_timezone_hint) % [ :timezone => Time.now.zone + " " + Time.now.formatted_offset ] %>
43:

44:
45:

plugins/redmine_maintenance_mode/app/views/settings/_redmine_maintenance_mode_settings.html.erb:42:in _09308e59f0466472a20b64685f686a4c' app/views/settings/plugin.html.erb:6:in block in _8dba6a574abc7f71c630a76cfd37c2c9'
app/views/settings/plugin.html.erb:4:in _8dba6a574abc7f71c630a76cfd37c2c9' lib/redmine/sudo_mode.rb:61:in sudo_mode'

Is there a solution for this error?
Many Thanks.

Michael Gehre