Thanks so much for your answer. I have applied the rules you mentioned on nginx for several times,but the problem remains unsolved.Now I am running the X3 photo-gallery on Apache and it is very nice.
I built a x3 photo gallery on my vps (server enviroment: nginx 1.16+php 7.2) according to the installation guide, the diagnostic shows everything works fine. But after uploading some images, I couldn't see the preview of the images, it's just a circle spinning all the time. When I changed nginx wi...