Getting error message when trying to upload new images, but images are showing on server

I have a new client that I’m doing some small website changes for. I did not originally build there website, nor is it using the Divi theme.

Here’s the issue: When I try to upload new images to the media library I get this error: “An error occurred in the upload. Please try again later.” However, when I look at the uploads folder via FTP, I can see the images on the server. The old images are still being shown in the media library too.

Here’s a list of everything I’ve tried while troubleshooting:

-The first thing I did was duplicate the site to my test server so I wouldn’t be troubleshooting on there live site, and to verify it wasn’t a server issue causing the error message.

-I deactivated ALL plugins.

-I changed the theme to a default WP theme.

-I changed the permalinks to the default settings.

-I repaired and optimized the database in phpmyadmin

-I Reinstalled WordPress

-I created a new .htaccess file

-I verified that the uploads folder and all subdirectories have 755 permission settings.

-I “reset” the plugins and themes folder.

Nothing worked.

Any ideas?