"Internal Service Error" when trying to Insert Images

Hi!

I recently downloaded a new theme and I’m trying to insert images into the home page slider, but whenever I try, an Internal Service Error comes up. Here’s what I’ve done to try to resolve the issue:

1. Tried to upload pictures with other themes to rule out theme-related issues. No luck. I can’t upload images into the home page sliders of any theme. I can, however, insert images into pages…

2. Deactivated all plugins both on the Dashboard and via FTP

3. Deleted .htaccess file

4. Tried to expand the memory by altering the wp-config.php file

None of these things have worked. Any ideas??

Thanks in advance, and sorry if this is a silly question with a simple solution. This is also my first time posting on the Support forum, so let me know if I’m not providing enough info ??