Token Mismatch Exception after upgrade to 5.4.

adding {{ csrf_field() }} inside your form might help--> https://laravel.com/docs/5.4/csrf

All that is in place. It is the upgrade which has broken it.

you might have the same situation --> https://laracasts.com/discuss/channels/general-discussion/keep-getting-tokenmismatchexception-verifycsrftokenphp-on-line-46?page=1

Yes...looks like something similar. I only get it in my tests though when I try to hit routes with get(), post(), json()

I can confirm that it is definitely just $this->json() which is causing the issue. Every time I make this call from my tests, a TokenMismatchException is thrown. I've upgraded two projects to L5.4 and it is happening in both.