Call to a member function getClientOriginalName() on null

we cannot see any code

public function visitorStore(Request $request) {
    $this->validate($request,[
            
            
            'visitorName'=> 'required',
            'organization' => 'required',
            'email' => 'required|unique:visitors|max:255',          
            'mobile' => 'required|unique:visitors|max:255',
            'vImage'  => 'required'
            
        ]);

            $visitor = new Visitor();

            $visitor->visitorName = $request->visitorName;
            
            $visitor->organization = $request->organization;
            $visitor->email = $request->email;
            $visitor->mobile = $request->mobile;

            $visitor->vImage = $request->hasFile('vImage');
            $image = $request->file('vImage');
            $name = $image->getClientOriginalName();
            $size = $image->getClientSize();
            $destinationPath = public_path('public/assets/img/');
            $image->move($destinationPath, $name); 
            

            $visitor->save();

        return redirect(route('visitor'))->with('successMsg','visitor added successfully');
    
    }

@Snapey Please check now.

Make sure that your form has the enctype="multipart/form-data" attribute.

@tykus thank you very much. Now my image is uploading and I can find it in my folder. But I am confused about one thing that there is nothing showing in my db table? so how can I display it and find which visitor has which image?

There are so many tutorials and previous questions about adding images.

Sorry, I'm bored answering these.

You are assigning a boolean here...

$visitor->vImage = $request->hasFile('vImage');

.. which isn't very useful! You need to store the destination path and filename instead.

Like @Snapey says, there are tonnes of examples of your problem here.