drupal_clear_css_cache appears to wipe out everything in files/css, which includes the aggregated CSS files of other sites running on the same installation, then repopulate it with the aggregated CSS files as needed.

If users are logged in that's ok, as CSS files are automatically regenerated, but for anonymous users the HTML pages of the other sites are cached and refer to the now-deleted CSS files.

A workaround could be to make sure each site uses a separate 'files' directory, but there should probably be a warning that this will happen as it's not obvious what's gone wrong.

Comments

hickory’s picture

hickory commented

Alternatively the aggregated CSS files could be prefixed with the name of the site, as color.module does for files in files/color, and only those CSS files belonging to the same site would be wiped when the cache is cleared.

Crell’s picture

Crell commented
Status: Active » Closed (duplicate)

Sharing a files directory between sites is asking for trouble in the first place. The correct answer is "don't", IMO. :-) Instead, use sites/default/files. Therefore, marking as a dupe of: http://drupal.org/node/98824