laravel throwing MethodNotAllowedHttpException for validation - php

Question

I tried to create a form with post method. When there was validation in the method, I faced with "Symfony \ Component \ HttpKernel \ Exception \ MethodNotAllowedHttpException" , but when i deleted validation it worked correctly. I don't know why!
HTML
#if(count($errors)>0)
<ul>
#foreach($errors->all() as $error)
<li style="color: #cc5200;"><i class="fas fa-times"></i>{{$error}}</li>
#endforeach
</ul>
#endif
<form method="post" action="{{route('test.added')}}">
#csrf
<input type="hidden" name="grade" value="{{$grade}}">
<input type="hidden" name="course" value="{{$course}}">
<input type="hidden" name="numbers" value="{{$numbers}}">
#for($i=0;$i<$numbers;$i++)
<div>
<span style="color: #cc5200">question{{$i+1}} :</span>
<textarea name="question[]" rows="2" style="width: 50vw">{{old('question')[$i]}}</textarea>
</div>
<div class="d-flex flex-row">
<div class="ml-1 mr-2">
<span>1-</span>
<input type="text" name="firstOption[]" style="width: 10vw" value="{{old('firstOption')[$i]}}">
<input type="radio" name="trueOption[{{$i}}]" value="1">
</div>
<div class="ml-1 mr-2">
<span>2-</span>
<input type="text" name="secondOption[]" style="width: 10vw" value="{{old('secondOption')[$i]}}">
<input type="radio" name="trueOption[{{$i}}]" value="2">
</div>
<div class="ml-1 mr-2">
<span>3-</span>
<input type="text" name="thirdOption[]" style="width: 10vw" value="{{old('thirdOption')[$i]}}">
<input type="radio" name="trueOption[{{$i}}]" value="3">
</div>
<div class="ml-1 mr-2">
<span>4-</span>
<input type="text" name="forthOption[]" style="width: 10vw" value="{{old('forthOption')[$i]}}">
<input type="radio" name="trueOption[{{$i}}]" value="4">
</div>
</div>
<br>
#endfor
<input type="submit" value="ok" style="float: left;color: white;background: #cc5200">
</form>
web.php
Route::post('/td-admin/test/add-finalStage','TestController#added')->name('test.added');
TestController
public function added(Request $request){
$request->validate([
'question.*'=>'required',
'firstOption.*'=>'required',
'secondOption.*'=>'required',
'thirdOption.*'=>'required',
'forthOption.*'=>'required',
'trueOption.*'=>'required',
]);
Test::create( ...
It made me crazy. please help me.