How to pass an optional image through my django, by accepting from views.py

Question

I want to accept an optional image from the user and pass it via my form, but it keeps popping up with multivaluedictkeyerror (i have added the enctype = "multipart/form-data") ps. im new to django

this is my views.py

def notes(request):
    if request.method == "POST":
        form =NotesForm(request.POST, request.FILES or None)
        if form.is_valid():
            notes  = Notes(user=request.user, title = request.POST['title'],description=request.POST['description'], pictures= request.FILES['pictures'])        #pictures= request.FILES['pictures']
            notes.save()
        messages.success(request,f"Notes added for {request.user.username} successfully!")
    else:
        form=NotesForm()
    notes=Notes.objects.filter(user=request.user)       #when logged in user wants to access all created notes, stores in notes variable
    context= {'notes':notes , 'form':form}
    return render(request,'dashboard/notes.html',context)

this is my models.py

from django.db import models
from django.contrib.auth.models import User

class Notes(models.Model):
    user = models.ForeignKey(User,on_delete=models.CASCADE) 
    title = models.CharField(max_length=200)
    pictures=models.ImageField(null=True,blank=True, upload_to="images/")
    description= models.TextField()

template,

<p class="description m-5 p-5">
                {{notes.description}}
                <br><center>
                {% if notes.pictures %}
                    <img class="fit-picture" style="border: 1px solid #555; max-width:80%; max-height:80%;" src = "{{ notes.pictures.url }}"> 
                {% endif %}               
            </p>

I accepted the passed value through request.Files[''], but it is a compulsory field, and i wanted an optional