Encoding::CompatibilityError: incompatible character encodings: ASCII-8BIT and UTF-8

https://sentry.gitlap.com/gitlab/gitlabcom/issues/143103/

Encoding::CompatibilityError: incompatible character encodings: ASCII-8BIT and UTF-8
  app/views/projects/wikis/edit.html.haml:37:in `_app_views_projects_wikis_edit_html_haml__1776368076757410303_70142724416760'
  app/controllers/projects/wikis_controller.rb:71:in `create'
    render action: "edit"
  lib/gitlab/i18n.rb:50:in `with_locale'
    yield
  lib/gitlab/i18n.rb:56:in `with_user_locale'
    with_locale(user&.preferred_language, &block)
  app/controllers/application_controller.rb:338:in `set_locale'
    Gitlab::I18n.with_user_locale(current_user, &block)
...
(169 additional frame(s) were not displayed)

Encoding::CompatibilityError: incompatible character encodings: ASCII-8BIT and UTF-8