Error when updating WordPress

This is a test site, the active site is

When updating WordPress to the latest version, the images are not visible when browsing with google chrome. In the media library some images are not visible.

We tried to make a massive adjustment of the size of the images (to 2700 × 1700) and the site ceased to be visible (we happened with the active site
We had to uninstall version 5.3 of WordPress, in the active site.
Can you help us with these errors?
Thank you