Find file that generated CSRF TOKEN error

Question

I set up the file handler for whenever any error occurs on the server, I receive an email with the details.

So today I got an email with the following error:

array(3) { ["message"]=> string(0) "" ["file"]=> string(104) "/var/www/infochat/vendor/Laravel/framework/src/Illuminate/Foundation/Http/Middleware/Verifycsrftoken.php" ["line"]=> int(71) }

I know what this error is, but the problem is I don’t know what caused it, IE, which file or code was responsible, so I can fix.

I didn’t find anything in the logs (I might have seen the wrong log). There was somewhere I could check to find out?