Permissions issues with ArcGIS Pro 3.0, Portal 10.8.1, and API for Python

[JCGuarneri]

I've found a curious apparent incompatibility between the Python API as installed with Pro 3.0 and Portal 10.8.1. When I try to search or access items, or perform admin tasks, I get permissions errors: 

Exception: You do not have permissions to access this resource or perform this operation.
(Error Code: 403)

For items, the only way to resolve this is to share the item publicly, which is not a good solution for the feature layers I'm working with. At first, I thought it might be the machine I was accessing it from, but I saw that it was working with our Dev Portal which is at 10.9.1. So I tested using another machine which still had Pro at 2.9, and it worked correctly. I then upgraded Pro on that machine to 3.0 and saw the same behavior. Is this a bug? Or is there a security setting, additional authentication step, etc, I need to be using? 

Here is an example of the code I'm using:

from arcgis import gis
portal = gis.GIS(r'https://myserver.myCompany.com/portal', username = r'superduperuser')
portal.content.get("ebea40d5aeg1beri5h3924306fe3142f")

[Anonymous User]

The looks like a typical proxy issue. I'm guessing your internet access goes through a proxy.

[RobertJost]

Can you elaborate on this and/or provide some additional resources for a solution?

[JCGuarneri]

Is there something different with how proxies are handled between Pro 2.9 and 3.0 and/or Enteprise 10.8.1 and 10.9.1? I ask because Pro 3.0 and Enterprise 10.8.1 is the only combination of those that doesn't work.

[Anonymous User]

I'll try... My corporate proxy goes through ports 8888. If ArcGIS Pro is trying to get out on 443 it will not work. You will need to declare HTTP/HTTPS using 8888

OR 

You will need to authenticate in python to get out through the proxy

add the following syntax:

response = requests.get(url, auth=('user', 'pass')

[Bahram-Jomehzadeh]

Having same issue trying to update a web map using jupyter notebook (arcgis pro 3.0.1)

map1.update()

Exception: You do not have permissions to access this resource or perform this operation.
(Error Code: 403)

[JCGuarneri]

Glad to hear I'm not the only one. What version of Portal/AGOL are you using?