Only ImageMagick can create thumbnails of PDFs, not PHP’s GD extension. WordPress will default to ImageMagick but only if it’s installed.
You can see which image editor is in use with this plugin:
https://ww.wp.xz.cn/plugins/health-check/
Go to Dashboard → Health Check → “Debug information” tab → “Media handling” subsection.
Turns out that a recent yum update borked my install of ImageMagick. I tried updating/reinstalling/uninstalling/reinstalling all the pieces, but kept running into compatibility errors. Apparently, it’s the CentOS provided version of php-pecl-imagick that was the problem. Here’s what finally did it for me:
sudo yum --enablerepo="remi-php56" install php-pecl-imagick
Sorry for thinking it was your plugin. It has always worked very well! 🙂
Good Morning!
I’m having the same error but I’m not trying anything with PDF, just same images, follow the link https://prnt.sc/je21dm