upload pdf file base64

I'm trying to upload a pdf file encoded in base64

the file got uploaded but it's not accessible " PDF document is damaged"

this is my code :

 public function handleUploadPdf(Request $request){

    $image = $request->input('image');  // your base64 encoded
    $image = str_replace('data:application/pdf;base64,', '', $image);
    $image = str_replace(' ', '+', $image);
    $imageName = str_random(10).'.'.'pdf';
    \File::put(public_path(). '/images/' . $imageName, base64_decode($image));

    return response()->json(['status'=>200]);

  }

what is causing this issue ? thank you in advance