Problem

Images do not load on an addon domain site.

Things Tried

There were a few things I tried. Here they are:

  • Upload images again
  • Delete all plugins
  • Delete all but one theme
  • Downgrade WordPress version
  • Check uplink configureation. All uploads/media should go into the folder /wp-content/uploads/.
  • Check whether the domain is whitelisted in its .htaccess file

Root Cause

The .htaccess file of the root domain does not whitelist the domain:

Solution

Whitelist addon domains in the .htaccess file of the root domain: