MethodNotAllowedHttpException in compiled.php line 8931 Laravel 5 - post

Question

I am getting an error of MethodNotAllowedHttpException in compiled.php line 8931. It was working fine but suddenly it started throwing this error. I created a view in directory resources/views/main/templates/submit-for-sale.blade.php and defined its route in routes.php as:
Route::get('/submit-for-sale', function () {
return view('main.templates.submit-for-sale');
});
This view submit-for-sale.blade.php contains a form whose form tag looks like:
<form id="submit-sale-form" action="{{route('main.submit-sale-form')}}" method="post" class="form-horizontal>
{{ csrf_field() }}
.............
</form>
View is loading perfectly.
Route to post form in routes.php
Route::post('/submit-sale-form', ['as' => 'main.submit-sale-form', 'uses' => 'MainController#submitSaleForm']);
Code in MainController.php
public function submitSaleForm(Request $request)
{
$parameters = Input::get();
foreach ([
'name' => 'Name',
'email' => 'Email',
] as $key => $label) {
if (!isset($parameters[$key]) || empty($parameters[$key])) {
return response()->json(
[
'success' => false,
'error' => "{$label} cannot be empty",
]
);
}
}
}
It worked fine 2 - 3 times same code but suddenly it started throwing this error. Your help and suggestions will be highly appreciated.
Thank You.