Item does not have a file (error 500) when uploading a PNG file to a portal using add item method - rest

Question

I am trying to setup a POST request method using the "Add Item" operation within a REST API for my portal so that the PNG images can be add and later updated. Currently my script uploads the item to the portal but when i try to download the file or share it then it opens a page saying "Item does not have a file . Error 500" I assume its something to do with how i am building the POST request. How should i send the file over the POST request so that i can later download and update the file . Here is my current code:
def add_item(username,files,type,title):
"""
Add an item to the portal
Input:
- file: path of the the file to be uploaded
- username: username of user uploads the item
Return:
- Flag with a list of messages
"""
# set request header authorization type
header = {
'Authorization': f'Bearer {token}'
}
# build url
u_rl = f"{portal}/sharing/rest/content/users/{username}/addItem"
# search for id
req = requests.post(url=u_rl, headers=header,files=files,data={ "type":type,"title":title,"f": "json"})
response = json.loads(req.text)
if 'error' in response.keys():
error = response["error"]
raise Exception(
f"Error message: {error['message']}", f"More details: {','.join(error['details'])}")
return response["success"] if 'success' in response.keys() else False
if __name__ == "__main__":
user = input("input your USERNAME: ")
password = getpass.getpass("input your PASSWORD: ")
portal = "https://cvc.portal"
token = generate_token(user, password, portal=portal)
files = {'upload_file': open(r'C:\Users\test.png','rb')}
type='Image',
title='An image'
add_item(user,files,type,title