Laravel pdf upload error

when i upload a pdf file which is 147KB of size it does not upload and it gives me this error The file must be a file of type: pdf. but when i upload a pdf file which is 505KB in size it works perfectly.

My controller

public function store(Request $request)
    {
        $this->validate($request,[
          'title' => 'required|unique:resources,title',
          'categories' => 'required',
          'file' => 'required|mimes:pdf|max:10000',
          'image' => 'required',
        ]);
        $image = $request->file('image');
        $slug = Str::slug($request->title);

        if(isset($image)){
          $currentDate = Carbon::now()->toDateString();
          $imageName = $slug.'-'.$currentDate.'-'.uniqid().'.'.$image->getClientOriginalExtension();

          if(!Storage::disk('public')->exists('resource')){
            Storage::disk('public')->makeDirectory('resource');
          }

          $resourceImage = Image::make($image)->stream();
          Storage::disk('public')->put('resource/'.$imageName,$resourceImage);
        }else{
          $imageName = "default.png";
        }
		
		if($request->file('file')){
			$file = $request->file('file');
			$fileName = time().'.'.$request->file->extension();  
            $request->file->move('storage/app/public/pdf/', $fileName);
		}

        $resource = New Resource();
        $resource->title = $request->title;
        $resource->slug = $slug;
        $resource->image = $imageName;
		$resource->file = $fileName;
        $resource->save();
        $resource->categories()->attach($request->categories);

        return redirect()->route('admin.resource.index')->with('message', 'Resource Added Successfully');
    }

Any help?