You've been redirected because COPS is not configured properly
Database error
Check if GD is properly installed and loaded
OK
Check if Sqlite is properly installed and loaded
OK
Check if libxml is properly installed and loaded
OK
Check if Json is properly installed and loaded
OK
Check if mbstring is properly installed and loaded
OK
Check if intl is properly installed and loaded
OK
Check if Normalizer class is properly installed and loaded
OK
Check if the rendering will be done on client side or server side
Client side rendering
Check if Calibre database path is not an URL
OK
Check if Calibre database file exists and is readable
File ./metadata.db not found,
Please check
- Value of $config['calibre_directory'] in config_local.php
- Value of open_basedir in your php.ini
- The access rights of the Calibre Database
- Synology users please read this