Why do 0kb photos appear in the image cache?

Question

opencart

Hello!
opencart 3.0.2.0.
There are more than 30,000 products on the site - each has 3-5 images. A bunch of thumbnails are created in the cache.
We began to notice that there are a lot of product photos in the image cache with zero size. As a result, they seem to be on the site (the system sees the path), but the file does not seem to exist. After clearing such zero photos from the cache, everything is fine, they are loaded normally. The photo extension is mostly png.
Because of what they can appear these photos with zero size? and How to fix it?

Answer 1

if the problem is massive, then see if there is an overload on the server