Incorrect filenames in load-scripts.php parameters

Do you have the “all-in-one-wp-security-and-firewall” plugin?

More info: https://wordpress.org/support/topic/load-scriptphp-fails-to-load?replies=3

Short answer, if so, disable the “Deny Bad Query Strings” option. If not, check for any other “security” plugins you have that might be doing dumb things.