Warning: Division by zero in theme_image_style_preview() (line 804 of /var/www/html/modules/image/image.admin.inc).

Warning: array_intersect_key(): Argument #1 is not an array in theme_image_style_preview() (line 806 of /var/www/html/modules/image/image.admin.inc).

I am receiving the above errors when I view several of the "stock" image styles on my site. I just moved my site from a development server to a production server, and the error does not occur on the development server version. I checked the directory permissions on the production server, and they appear to be consistent with the development server's permissions.

One really strange thing occurs when I view the source on the "preview image" in the admin back-end of one of those styles that has the issue. When I do, it shows the following path being called (which is, of course, not a valid path):


The "sites/default/files/styles/large/public/" part seems to be part of the issue, but I am not sure how that got there. All of my custom image styles work fine.


  • 1
    Have a look at theme_image_style_preview source. Your error comes from a missing sample image or failure to generate a derivative image from that. May 11, 2014 at 23:17
  • @DavidThomas why not to post that as an answer?
    – Mołot
    May 12, 2014 at 6:46
  • @David Thomas, that does not seem to be the source of the issue. When I change the code referencing "theme_image_style_preview" in image.admin.inc, that seems to control the "original" image... not the "preview" image for the image style I am editing.
    – hockey2112
    May 12, 2014 at 14:29

2 Answers 2


I did:

chmod 777 drupal/sites/example.com/files/styles

and the error went away and my drupal 7 new image-style worked.


Apparently it is not safe to chmod files to 777.

A preferred way is to chmod files to 644, directories to 755 and set the ownership to the webserver, so the webserver can write files.

Here's a script for Ubuntu:

# Change directory permissions to 755.
find sites/default/files -type d -exec chmod 755 {} +
# Change folder permissions to 644.
find sites/default/files -type f -exec chmod 644 {} +
# Set ownership to webserver.
chown -R www-data:www-data sites/default/files

Learn more on - Recommended directory permissions.

  • This should be the accepted answer as setting the files directory permissions to 777 is not a good answer.
    – DrCord
    Jun 3, 2016 at 17:40

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