I’m running WP 5.4.2 on a site that I’ve been busy trying to complete. Last week, I uploaded a boatload of PNG files to complete a batch of custom posts. I mention this to substantiate that I have no expectation of encountering problems when attempting to add media items to the library.
I’m attempting to add images to a page I’m editing, and every attempt results in the same error message:
Post-processing of the image failed likely because the server is busy or does not have enough resources. Uploading a smaller image may help. Suggested maximum size is 2500 pixels.
These are minuscule SVGs and JPEG files.
Just as the image size is not an issues, my theme (GeneratePress, with GP Premium, running under a child theme) is not the issue either. I switched temporarily to Twenty-Twenty and saw the same problem with it active.
I saw several discussions of the Big Image Size bug and tried the recommended fix:
add_filter( 'big_image_size_threshold', '__return_false' );
This had no effect, so I removed the code from my child theme.
I’m dead in the water till I can get around this problem. Because the site is not public yet, I’m not posting the URL here.
Many thanks to anyone who can shed some light on this.