11 August 2015

Fixing broken thumbnails in Drupal


If your autoscaled images are not loading on Drupal then here are some steps to take to troubleshoot the problem.

Firstly, if you have logging enabled then visit http://yoursite.com/admin/reports/dblog to see a list of the events.

If you see events with the message "Unable to generate the derived image located at...." then check the permissions on your files directory.  This is usually /sites/default/files.

Then check that the GD library is installed for PHP.  On Ubuntu you can install it with apt-get install php5-gd

If you don't see any events then try opening the image url in a new tab on your browser to confirm that your web server is properly rewriting the request to index.php instead of trying to serve a file out of the directory.

On Nginx you should consider using location blocks like this:

   # These next locations help with thumbnails - https://www.drupal.org/node/2374961  
   location @rewrite {  
     rewrite ^/(.*)$ /index.php?q=$1 last;  
   }  
   location ~ ^/sites/.*/files/styles/ {  
     try_files $uri @rewrite;  
   }  

This makes sure that requests to locations in the styles directory are routed to index.php if the requested file does not exist in the filesystem.
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