Hello
After sending the database version Odoo 12 to https://upgrade.odoo.com/ to migrate it to Odoo 14, when I try to log in I get this error.

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

Error: The target selector was not found.
Use "@extend %o-we-background-layer !optional" to avoid this error.
on line 3500 of stdin

@extend %o-we-background-layer;

------------^
This error occured while compiling the bundle 'web.assets_frontend' containing:
- /web/static/lib/bootstrap/scss/_functions.scss
- /web/static/lib/bootstrap/scss/_mixins.scss
- /web/static/src/scss/bs_mixins_overrides.scss
- /web/static/src/scss/utils.scss
- /web/static/src/scss/primary_variables.scss
- /web_enterprise/static/src/scss/primary_variables.scss
- /web_editor/static/src/scss/web_editor.variables.scss
- /web_editor/static/src/scss/13_0_color_system_support_primary_variables.scss
- /mail/static/src/scss/variables.scss
- /portal/static/src/scss/primary_variables.scss
- /account/static/src/scss/variables.scss
- /marketing_automation/static/src/scss/variables.scss
- /web_editor/static/src/scss/secondary_variables.scss
- /web_enterprise/static/src/scss/secondary_variables.scss
- /web/static/src/scss/secondary_variables.scss
- /portal/static/src/scss/bootstrap_overridden.scss
- /web_editor/static/src/scss/bootstrap_overridden.scss
- /web/static/src/scss/bootstrap_overridden_frontend.custom.web.assets_frontend.scss
- /web/static/lib/bootstrap/scss/_variables.scss
- /web/static/src/scss/import_bootstrap.scss
- /web/static/src/scss/bootstrap_review.scss
- /web/static/src/scss/base_frontend.scss
- /web/static/src/scss/lazyloader.scss
- /web/static/src/scss/navbar_mobile.scss
- /web/static/src/scss/notification.scss
- /web_editor/static/src/scss/web_editor.common.custom.web.assets_frontend.scss
- /web_editor/static/src/scss/web_editor.frontend.scss
- /portal/static/src/scss/bootstrap.extend.scss
- /portal/static/src/scss/portal.scss
- /portal_rating/static/src/scss/portal_rating.scss
- /payment/static/src/scss/portal_payment.scss
- /payment/static/src/scss/payment_form.scss
- /sale/static/src/scss/sale_portal.scss
- /rating/static/src/scss/rating.scss
- /google_recaptcha/static/src/scss/recaptcha.scss