The theme or an additional directory has no directory with the configured
source name. If the theme has no SCSS, choose a different theme, or ignore
the message: the other directories still compile.
CSS directory is not writable: PATH
The web server user cannot write the output directory, or cannot create
it. On a development site, fix the permissions. Otherwise compile with
drush scss:compile as a user that can write to the code base.
There are no .scss files to compile for: PATH
The source directory has only partials or ignored files.
Error compiling SASS file FILE: …
scssphp could not compile the file. The message shows the line and
column. Other files still compile.
Sass modules are not implemented yet.
scssphp 2.1 does not support @use and @forward. Use @import.
Cannot locate the scssphp library.
The module was not installed with Composer. Run
composer require drupal/scss.
PATH must be relative to the Drupal root, and cannot contain .. or a stream wrapper.
Settings paths must stay inside the Drupal root. Use a path such as
modules/custom/my_module.
Check that you are logged in (or that Compile while logged out is on),
that the page was not served from the internal page cache, and that the
check interval has passed. Pages served to anonymous users from the page
cache never reach the module.
The site fails with a TypeError about a constructor after updating.
Releases after 2.1.9 changed the services' constructor arguments. Run
drush updb or drush cr to rebuild the container.
Where did my CSS file go?
A source file in a subdirectory is written to the same subdirectory of the
output directory, for example css/layout/grid.css. Releases up to 2.1.9
wrote every file to the top of the output directory.
Can I keep compiled CSS out of version control?
Yes, if every environment compiles it: run drush scss:compile in the
deployment or CI step that builds the code base.