Use of undefined constant NONCE_SALT
Use of undefined constant NONCE_SALT ... in Shortcode.php on line 192
Cause & solution
The problem will be related to a missing constant in your wp-config.php file. This file should contain an automatically generated NONCE_SALT constant as you see in the sample wp-config.php file at this line:
define('NONCE_SALT', 'put your unique phrase here');
In your case this seems to be missing for some reason. You should generate a new one:
and enter it into the wp-config.php file as you saw above and that will fix the problem!