Security Policy Errors

How to Fix Information Barriers Block Policy Errors in Microsoft 365

Khadija Khan Oct 10, 2026 869 views

Question details

Users are encountering generic internal server errors when attempting to create blocked Information Barriers policies, despite allow policies functioning normally.

Troubleshooting Information Barriers Block Policy Errors in Microsoft 365

Product: Microsoft 365
Device & OS: not provided
Scenario: Creating blocked Information Barriers policies via the Microsoft 365 admin interface or Exchange Online PowerShell.
Observed behavior: Allow policies are created successfully, but attempting to create blocked policies triggers a generic internal server error and fails to apply.

Before you start

Ensure you are assigned the Compliance Administrator or Global Administrator role in Microsoft 365 and have access to Exchange Online PowerShell before modifying policies.

Solution 1Recommended

Upgrade to Information Barriers Version 2

Transitioning to Information Barriers v2 can resolve structural policy errors by properly enabling multiple segment support.

Legacy Information Barriers (v1) may struggle with overlapping segment logic. Upgrading to v2 requires clearing out old configurations first.

Connect to PowerShell

Launch Exchange Online PowerShell and authenticate using your Microsoft 365 administrator credentials.

Remove existing policies

Identify and delete all existing Information Barriers segments and policies to ensure a clean slate for the v2 upgrade.

Enable v2 multiple segments

Follow the official Microsoft documentation to enable multiple segments for Information Barriers version 2.

Recreate segments and policies

Recreate your segments and attempt to create the block policies again in the newly upgraded v2 environment.

Solution 2

Include Source Segment in Allow Policies

Adjust the parameters of your allow policies to ensure they do not create underlying logical conflicts with your block policies.

Solution 3

Gather Diagnostics and Escalate to Support

If generic internal server errors persist after configuration checks, backend Microsoft support intervention is required.

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Frequently Asked Questions

Why am I getting a generic internal server error for block policies but not allow policies?

This discrepancy often occurs due to structural conflicts in how Information Barriers version 1 handles overlapping segments. Block policies require strict logical separation, which might fail on the backend if previous allow policies or segment configurations conflict.

How do I correctly format an allow policy in PowerShell to avoid conflicts?

When creating an allow policy, you must include the source segment in the allowed segments list. For example, to allow Segment A to communicate with Segment B, use: New-InformationBarrierPolicy -Name "AToB" -AssignedSegment "A" -SegmentsAllow "A,B".

What should I do before upgrading to Information Barriers v2?

Before upgrading to v2 to enable multiple segments, Microsoft documentation requires that you completely delete all existing Information Barriers segments and policies from your organization.

What information does Microsoft Support need to fix this error?

Microsoft Support will need a full screenshot of the generic internal server error, any correlation IDs displayed, and the exact PowerShell command string you used to initiate the policy creation.

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