MethodNotAllowedHttpException in RouteCollection.php line 219

Check your form tag

<form action="/path/" method="post">

in here "/path/" should be "/path" , do not use "/" at the end.

Since you're setting the method on the post's update to be patch, be sure you open your form to use that method:

{!! Form::open(['method' => 'patch']) !!}

If you're not using the Form class, you can also just ensure there's a hidden element called _method underneath the form:

<input name="_method" type="hidden" value="PATCH">

Similarly, if you're sending this data via AJAX, just add a _method key to the payload set to 'PATCH' before sending the request via POST. Some browsers (IE 7/8) do not support PATCH HTTP through XMLHttpRequest

Your other option is to change your route to accept POST data instead:

Route::post('posts/store-new-post', 'PostsController@store');
Route::post('posts/{slug}', 'PostsController@update');