I have created a form which is having a lot of fields and user can create an unlimited field in it. If a user spends more time on it CSRF token get expires and when he clic
Just add this to your script
And make sure you have added token to your meta tag like below.
I hope this will work for you.
Link https://laravel.com/docs/5.4/csrf#csrf-x-csrf-token
If you still found the same issue then please review these pieces of stuff
Handling expired token in Laravel
https://laracasts.com/discuss/channels/laravel/csrf-token-mismatch-error-on-session-timeout-form?page=1
And Make sure you take a look at all answers, not only checked one