Next time please use a meaningful title.

Google is your friend: https://github.com/muk-it/muk_dms/issues/73. Please install the newest version of your MuK-Module and update it.

in fact I changed something in the file and then I put the file back as it was before except that this time the error message appears 

here is the error message :

The style compilation failed, see the error below. Your recent actions may be the cause, please try reverting the changes you made.

Error: no mixin named mk-flex-container

       Backtrace:
       	/stdin:10207
        on line 10207 of /stdin

>> 	@include mk-flex-container(column);
   ----------^
This error occured while compiling the bundle 'web.assets_backend' containing:
    - /web/static/lib/bootstrap/scss/_functions.scss
    - /web/static/lib/bootstrap/scss/_mixins.scss
    - /web/static/src/scss/utils.scss
    - /web/static/src/scss/bs_mixins_overrides.scss
    - /web/static/src/scss/primary_variables.scss
    - /web_editor/static/src/scss/web_editor.variables.scss
    - /mail/static/src/scss/variables.scss
    - /portal/static/src/scss/primary_variables.scss
    - /website/static/src/scss/primary_variables.scss
    - /website/static/src/scss/options/colors/user_color_palette.scss
    - /website/static/src/scss/options/colors/user_theme_color_palette.scss
    - /web/static/src/scss/secondary_variables.scss
    - /website/static/src/scss/secondary_variables.scss
    - /web/static/src/scss/bootstrap_overridden.scss
    - /web_editor/static/src/scss/bootstrap_overridden.scss
    - /web/static/src/scss/import_bootstrap_part1.scss
    - /web/static/src/scss/bs_mixins_overrides.scss
    - /web/static/src/scss/import_bootstrap_part2.scss
    - /web/static/src/scss/bootstrap_review.scss
    - /web/static/src/scss/webclient_extra.scss
    - /web/static/src/scss/webclient_layout.scss
    - /web/static/src/scss/webclient.scss
    - /web/static/src/scss/domain_selector.scss
    - /web/static/src/scss/model_field_selector.scss
    - /web/static/src/scss/progress_bar.scss
    - /web/static/src/scss/dropdown.scss
    - /web/static/src/scss/dropdown_extra.scss
    - /web/static/src/scss/tooltip.scss
    - /web/static/src/scss/debug_manager.scss
    - /web/static/src/scss/control_panel.scss
    - /web/static/src/scss/fields.scss
    - /web/static/src/scss/fields_extra.scss
    - /web/static/src/scss/views.scss
    - /web/static/src/scss/pivot_view.scss
    - /web/static/src/scss/graph_view.scss
    - /web/static/src/scss/form_view.scss
    - /web/static/src/scss/form_view_extra.scss
    - /web/static/src/scss/list_view.scss
    - /web/static/src/scss/list_view_extra.scss
    - /web/static/src/scss/kanban_dashboard.scss
    - /web/static/src/scss/kanban_examples_dialog.scss
    - /web/static/src/scss/kanban_column_progressbar.scss
    - /web/static/src/scss/kanban_view.scss
    - /web/static/src/scss/kanban_view_mobile.scss
    - /web/static/src/scss/web_calendar.scss
    - /web/static/src/scss/search_view.scss
    - /web/static/src/scss/search_view_mobile.scss
    - /web/static/src/scss/dropdown_menu.scss
    - /web/static/src/scss/search_view_extra.scss
    - /web/static/src/scss/data_export.scss
    - /base/static/src/scss/onboarding.scss
    - /web/static/src/scss/base_settings.scss
    - /web/static/src/scss/report_backend.scss
    - /base_import/static/src/scss/base_import.scss
    - /web_diagram/static/src/scss/diagram_view.scss
    - /web_editor/static/src/scss/web_editor.common.scss
    - /web_editor/static/src/scss/web_editor.backend.scss
    - /mail/static/src/scss/announcement.scss
    - /mail/static/src/scss/discuss.scss
    - /mail/static/src/scss/abstract_thread_window.scss
    - /mail/static/src/scss/thread_window.scss
    - /mail/static/src/scss/composer.scss
    - /mail/static/src/scss/chatter.scss
    - /mail/static/src/scss/followers.scss
    - /mail/static/src/scss/thread.scss
    - /mail/static/src/scss/systray.scss
    - /mail/static/src/scss/mail_activity.scss
    - /mail/static/src/scss/activity_view.scss
    - /mail/static/src/scss/kanban_view.scss
    - /mail/static/src/scss/attachment_box.scss
    - /partner_autocomplete/static/src/scss/partner_autocomplete.scss
    - /muk_dms/static/src/scss/variables.scss
    - /muk_dms/static/src/scss/directory_kanban.scss
    - /muk_dms/static/src/scss/file_kanban.scss
    - /muk_web_preview/static/src/scss/variables.scss
    - /muk_web_preview/static/src/scss/sidebar.scss
    - /muk_web_preview/static/src/scss/binary.scss
    - /muk_web_preview/static/src/scss/content.scss
    - /muk_web_preview/static/src/scss/pdf.scss
    - /muk_web_preview/static/src/scss/loading.scss
    - /muk_web_preview/static/src/scss/manager.scss
    - /muk_web_preview/static/src/scss/dialog.scss
    - /muk_web_preview/static/src/scss/form.scss
    - /muk_dms_actions/static/src/scss/form_actions.scss
    - /muk_dms_actions/static/src/scss/list_actions.scss
    - /muk_dms_actions/static/src/scss/kanban_actions.scss
    - /muk_dms_view/static/src/scss/base.scss
    - /muk_dms_view/static/src/scss/main.scss
    - /muk_dms_view/static/src/scss/dialog.scss
    - /muk_dms_view/static/src/scss/preview.scss
    - /muk_web_preview_opendocument/static/src/scss/document.scss
    - /website/static/src/scss/website.backend.scss
    - /website_theme_install/static/src/scss/website_theme_install.scss
    - /web_responsive/static/src/css/web_responsive.scss
    - /backend_theme_v12/static/src/scss/style.scss
    - /backend_theme_v12/static/src/scss/sidebar.scss
    - /sales_team/static/src/scss/sales_team_dashboard.scss
    - /web_settings_dashboard/static/src/scss/dashboard.scss
    - /muk_web_utils/static/src/scss/variables.scss
    - /muk_web_utils/static/src/scss/mixins.scss
    - /muk_web_utils/static/src/scss/switch.scss
    - /muk_web_utils/static/src/scss/dropzone.scss
    - /muk_web_utils/static/src/scss/module.scss
    - /muk_web_utils/static/src/scss/color.scss
    - /muk_web_utils/static/src/scss/image.scss
    - /muk_web_utils/static/src/scss/copy.scss
    - /muk_web_utils/static/src/scss/share.scss
    - /muk_web_utils/static/src/scss/notification.scss
    - /muk_web_searchpanel/static/src/scss/variables.scss
    - /muk_web_searchpanel/static/src/scss/kanban_view.scss

Hello, 

You can clone odoo addons and change your addons path in odoo config. file and restart odoo services.

Maybe your problem solved.

Thanks.

Hi,

Can you specify what is the error message that you are getting ? If you just opened that file only without changing anything, there is no chance for the error. Please update the question along with the error message that you are getting.

Thanks