Hello brandsi,
Thank you for contacting us. I recommend enabling debugging as it may provide a more detailed error message. Disable your other 3rd party plugins. An easy way to accomplish this is to rename the /plugins folder, then rename it back after testing. Try testing with a default theme installed such as “twenty seventeen”. Check your servers error logs for additional messages. Check your mod_security log for any blocks there. Try renaming your .htaccess file, which will disable the rules for testing.
Thank you,
John-Paul