Incorrect AES key length (15 bytes)?

Question

**I Want to integreted paytm payment integration but its occure error any one tell me how to solve this error ....................................................................................................... **

In below code return show above error ?

  Checksum.py
    def generate_refund_checksum(param_dict, merchant_key, salt=None):
        for i in param_dict:
            if("|" in param_dict[i]):
                param_dict = {}
                exit()
        params_string = __get_param_string__(param_dict)
        salt = salt if salt else __id_generator__(4)
        final_string = '%s|%s' % (params_string, salt)
    
        hasher = hashlib.sha256(final_string.encode())
        hash_string = hasher.hexdigest()
    
        hash_string += salt
    
        return __encode__(hash_string, IV, merchant_key)

views.py

def checkout(request):
    if request.method=="POST":
        items_json = request.POST.get('itemsJson', '')
        name = request.POST.get('name', '')
        amount = request.POST.get('amount', '')
        email = request.POST.get('email', '')
        address = request.POST.get('address1', '') + " " + request.POST.get('address2', '')
        city = request.POST.get('city', '')
        state = request.POST.get('state', '')
        zip_code = request.POST.get('zip_code', '')
        phone = request.POST.get('phone', '')
        order = Orders(items_json=items_json, name=name, email=email, address=address, city=city,
                       state=state, zip_code=zip_code, phone=phone, amount=amount)
        order.save()
        update = OrderUpdate(order_id=order.order_id, update_desc="The order has been placed")
        update.save()
        thank = True
        id = order.order_id
        # return render(request, 'shop/checkout.html', {'thank':thank, 'id': id})
        # Request paytm to transfer the amount to your account after payment by user
        param_dict = {

                'MID': 'aLIuwT24854788821719',
                'ORDER_ID': str(order.order_id),
                'TXN_AMOUNT': str(amount),
                'CUST_ID': email,
                'INDUSTRY_TYPE_ID': 'Retail',
                'WEBSITE': 'WEBSTAGING',
                'CHANNEL_ID': 'WEB',
                'CALLBACK_URL':'http://127.0.0.1:8000/shop/handlerequest/',

        }
    
    **param_dict['CHECKSUMHASH'] = Checksum.generate_checksum(param_dict,MERCHANT_KEY)**
        return render(request, 'shop/paytm.html', {'param_dict': param_dict})

Show above error due to in views.py this line

param_dict['CHECKSUMHASH'] = Checksum.generate_checksum(param_dict,MERCHANT_KEY)

Answer 1

Finally i solved this above error by encoding see below I did in checksum.py file before solved

Checksum.py        
return __encode__(hash_string, IV, merchant_key).encode('utf-8')
after solved
Checksum.py        
return __encode__(hash_string, IV, merchant_key).encode('utf-8')