Since version 4.7 WordPress supports the creation and generation of thumbnails for your PDF files. If this does not work in your WordPress, it is probably due to a missing component on your server. We recommend that you take the following steps to generate PDF thumbnails correctly:
- Login to your WordPress instance
- Navigate to Plugins > Add new > Search for “PDF Thumbnails Support Test” or directly download and install from here: https://wordpress.org/plugins/pdf-thumbnails-support-test/
- Navigate to Tools > PDF Thumbnails Support Test and check your missing components.
If you are missing a component, it can look like this:
If you have no technical knowledge, it is best to contact your technical contact person (e.g. your hoster)