Why is wordpress not loading 8 bit png?

Question

PNG

Moreover, in fact, it downloads them, they get into the upload folder, but then php falls further. If you load the browser, then "500 server error". It would seem that the problem is in the version of php or htaccess, or somewhere else I screwed up, but 24 bit pngs are loaded without problems. There is a suspicion that pngout somehow overly aggressively optimizes the file, which php does not force, but what to do about it? If you load not from an article, but from media files, and then return to the article, then the files are visible in the catalog, but as icons, without previews. But they can be added to the article and everything is displayed correctly, even after publication.
Is there any way to deal with this?

Answer 1

I think it's better for you to go here (and write) ru.forums.wordpress.org , and even better here https://wordpress.org/support/