After migrating a site from D6 to D7 with
drush site-upgrade, I notice that some public contents in the D6 version refered to pictures with URIs like for instance
/system/files/logo.png, instead of the more efficient
system directory on disk and no URL rewriting that I can see, so I assume the first form goes to Drupal for routing.
The problem is that with D7 post-upgrade, such references lead to a "Page not found" error so the pictures are broken.
As a test, if I drop
/sites/default/files/, D6 seems to be happy to serve http://example.com/system/files/somefile.png despite the fact that the file is not known anywhere in its database. But D7 apparently doesn't do that.
/system/files a hardcoded path component that means something to D6 and not D7?
/admin/config/media/file-system, the download method is set to "Public local files served..."
How to solve this with Drupal 7? Is there a configuration setting somewhere that I'm missing?