SQLSTATE[42S22] error in Laravel 6 update function

I'm trying to run a update function in my laravel app but every time when i run the function it gives me this error,

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'id' in 'where clause' (SQL: update apps set domain = Testinput.test.com, apps.updated_at = 2020-03-30 13:18:32 where id is null)

Here is my update function in the controller,

public function update(Request $request,App $app, $id)
    {

        $this->validate($request, [
            'domain' => ['required', 'string','min:2', 'max:255'],
        ],$request->all());

        $fullDomain = $request->domain;
        $app->domain=$fullDomain;
        $app = App::where('appId','=','1')->first()->update($request->all());
        return Redirect::back()->with('success',__('sentence.User updated successfully')); 
    }

I dont't have a column called id in my apps table my column is appId

via Chebli Mohamed