The sign-in error code 53003 indicates that the Conditional Access policies set by the organization that manages the resource (in this case, likely your organization) are blocking the external user from accessing the workspace. Conditional Access policies can indeed apply to external users if they are set up that way. It's a common misconception that Conditional Access policies only affect internal users, but they can be configured to enforce specific requirements for anyone trying to access resources, whether they are internal or external. Here's what you can do to resolve this issue:
- Review Conditional Access Policies: Check the Conditional Access policies configured in your organization's Azure Active Directory (or equivalent service) to see if any of them might be restricting access based on criteria such as:
- Location (e.g., only allowing access from certain IP ranges or geographic regions).
- Device compliance (e.g., requiring devices to be domain-joined or compliant with specific security policies).
- Approved client apps (e.g., only allowing access from certain browsers or applications).
- Modify Policies if Necessary: If you identify a policy that could be blocking the external user, you may need to modify it to allow access for external users. This might include:
- Adding a specific exception for the external user or their organization.
- Temporarily relaxing the policy to allow their access.
- Coordinate with External User’s IT Department: If the issue seems to be on their end, work with the external user's IT department to ensure that their access attempts meet the conditions set by your Conditional Access policies.
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