Error: 403: Forbidden when signing into CAS on MacOS/iOS device

Symptoms

If you are on a Mac or iOS device, you may be presented with a "403: Forbidden" error, as shown in the screenshot below, after you enter your eID and password when signing in on CAS.

Image

Environment

macOS

iOS

Solution

You should check and make sure that your time zone/clock settings are set automatically on your device:

  • iOS: 
    • Navigate to Settings > General > Date & Time and make sure Set Automatically is toggled on.
  • MacOS: 
    • Navigate to the Apple Menu > System Settings > General (in the sidebar) > Date & Time and turn on Set time and date automatically.

Cause

Your time zone/clock settings on your device do not match the current time.

Outcome

You will not encounter the error anymore and will be able to successfully sign in.

Solution Properties

Keywords
CAS SSO DUO
Solution ID
240529121721493
Last Modified Date
08/26/2025 03:12:53 PM
Taxonomy
  • Network and Security > Single Sign-On
  • Software > Microsoft 365
Collections
  • VCU (Public)
  • Technology Services
  • IT Professionals
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