Hi,
I'm not sure exactly what code are you using or how are you're executing it on demand. But I suspect, that the error in the code is appearing when you try to run it using a URL (on demand).
You can turn on WordPress debugging and see if any detailed errors or warnings are logged in the server's error logs.
( ref: https://wordpress.org/support/article/debugging-in-wordpress/ )
When a visitor visits any page of your website ( for example "xyz.com" ), any custom functions attached to "Front-end" will be available for execution.
For example, suppose you have a custom shortcode that counts and saves views for how many times a page/post is visited. For this snippet, you'll need it to be available for the "Front-end".
When a logged-in user visits any WordPress admin area page of your website ( for example "xyz.com/wp-admin" ), any custom functions attached to "WordPress admin" will be available for execution.
For example, suppose you have a custom code that loads a certain CSS or JS file, only for admin area pages. For this snippet, you'll need it to be available for the "WordPress admin".
And lastly, as the name indicates, if you need some custom code to be available for execution, when an AJAX request is made (irrespective of whether it is a front-end page or a back-end), the "AJAX calls" option should be checked for that snippet.
For example, suppose you have a custom shortcode that calculates some values inside a view's loop item. If you've checked the "Front-end" option for its snippet, but not the "AJAX calls", the shortcode will work when the view will first load, but not, when the results are updated using AJAX (without any page reload).
The custom function attached to the "cred_save_data" hook needs to be executed when the form is submitted on the front-end. So if the form is submitted without AJAX, make sure that the "Front-end" option for the snippet is checked and if the form is using AJAX submission, then make sure that the "AJAX calls" option is checked.
One last point to note is that adding custom code through the Toolset custom code feature and selecting the Run context (Front-end, WordPress admin, and AJAX calls) doesn't mean that the code will execute with each page load or AJAX call. This only means that the code will be available in the relevant Run context and when its relevant action is performed, only then it will execute.
For instance, the custom function attached to the "cred_save_data" hook will only execute when the form will be submitted and not just with the page load. Through snippet's Run context, you can only specify the availability or eligibility of the snippet's inclusion.
regards,
Waqar
