3 Hassle-free Ways to Disable WordPress PDF Thumbnail

WordPress PDF thumbnail refers to the image preview of the first page of a PDF file. It gives readers a quick overview of what the PDF is about. Since the release of WordPress 4.7, a PDF thumbnail will be automatically generated right after you upload the file in your media library.

Still, you may want to disable this feature for some reason. The default WordPress thumbnail feature can conflict with PDF plugins. Besides, too large thumbnail files can eat up your server disk storage.

In this article, we’ll explain why you should disable the WordPress PDF thumbnail in more detail. Then, 3 different methods to solve the issue will be presented.

Let’s get started.

Why Disabling WordPress PDF Thumbnail

Imagine you own a lot of PDF files in the WordPress media library. Thumbnails make it easier for you as well as editors and authors working on your site to reach the right file more quickly. Along with the file name, thumbnails tell them what each file is about without having to open it.

However, considering other benefits, site owners prefer disabling this feature. They may already install a PDF plugin that helps create PDF thumbnails. This can cause conflicts with WordPress’s built-in feature.

Another reason relates to website server storage. Whenever you upload a media file, WordPress will auto-create multiple versions of the file with different sizes. This requires you to clean up your WordPress images to avoid wasting server disk space.

And the same thing goes for PDF files. It won’t matter if you have one or a few thumbnail images. In case you have hundreds of PDFs and thumbnails, they’ll occupy most of the server storage. This will result in slow loading speed and poor site performance.

How to Remove WordPress PDF Thumbnails

#1 Using cPanel File Manager

To disable PDF thumbnail via cPanel File manage, you firstly need to log in to your FTP client, then choose My cPanel.

Under the FILES section, you’ll see a list of options to choose from. Simply select File Manager.

 

It now shows up all WordPress folders. Find the wp-content one and click on theme.

The next step is finding and opening your current theme folder. In the list of theme files, click on the functions.php file and press the Edit option to make changes.

Copy the following code into the ​​functions.php file and you’re done.

/**
 * Disable PDF thumbnail generation. 
 */
function disable_pdf_previews() {
$fallbacksizes = array();
return $fallbacksizes;
}
add_filter('fallback_intermediate_image_sizes', 
 'disable_pdf_previews');
After saving the file, you should go back to your media library, try to upload a new PDF to double-check if WordPress stops creating a thumbnail for your file.

#2 Using Functions.php Feature

Apart from editing the functions.php file on the server, you can handle this task right in your WordPress admin dashboard. The guide below will show you how to achieve that with ease.

1. Log into your WordPress admin
2. Head to Appearance → Theme Editor in the left-hand navigation menu
   
3. Open the functions.php file on the right-side menu
4. Enter this code to the file:

   function wpb_disable_pdf_previews() { 
   $fallbacksizes = array(); 
   return $fallbacksizes; 
   } 
   add_filter('fallback_intermediate_image_sizes', 'wpb_disable_pdf_previews');

5. Save your changes

The way this code works is simple. It will define the thumbnail size to 0 which means WordPress can create no thumbnail images for your PDFs. You can upload a new PDF file to the media library making sure that WordPress won’t generate it a thumbnail.

Remember to back up your site or create a child theme and make changes there, otherwise, it affects the entire site performance. Even worse, it will break the site down.

#3 Using Disable PDF Thumbnails Plugin

There are not many plugin options for you to stop WordPress from auto-generating thumbnail images for PDF files. The lightweight Disable PDF Thumbnails plugin can be a good try.

Despite the recent launch and a low number of active installations, Disable PDF Thumbnails does a great job at stopping WordPress from creating thumbnails for your newly uploaded PDF files.

All you need to do include install and activate the plugin. Here are the steps:

1. Go to Plugins → Add New
2. Type “disable PDF thumbnails” in the keyword box
3. Press Install Now and Activate buttons

When you don’t plan to continue disabling thumbnail preview, simply deactivate the plugin.

Ready to Stop WordPress PDF Thumbnail Preview?

Thumbnail images prove useful in making it easy for you to quickly preview the first page of your PDF files. However, some users try to disable this feature for a couple of reasons. You don’t have to worry about these images taking too much of your server space or causing conflicts with other PDF plugins.

We’ve instructed you to disable the WordPress PDF thumbnail in 3 ways. You can use cPanel File Manager or the functions.php file if getting familiar with coding. You’re tech-savvy? Simply make use of the Disable PDF Thumbnails plugin.

If you still have any questions about how to remove thumbnail images of PDF files or just want to share your experience, drop us a line in the comment.