Security Policy Errors

How to Fix Client Errors in Microsoft Attack Simulation Training

Kushani Nimanthika Oct 16, 2026 869 views

Question details

A Global Administrator encounters a client error preventing the phishing landing page selection screen from loading during a malware-attachment attack simulation creation.

How to Fix Client Errors in Microsoft Attack Simulation Training

Product: Microsoft 365
Device & OS: not provided
Scenario: Creating a malware-attachment attack simulation in the Microsoft 365 Defender portal.
Observed behavior: A client error is displayed. After dismissing the error, the Target Users step functions, but the phishing landing page selection screen fails to load.

Before you start

Ensure you are logged in with Global Administrator or Security Administrator credentials in the Microsoft 365 portal before troubleshooting simulation errors.

Solution 1Recommended

Gather Error Details and Escalate to Microsoft Support

Client errors during attack simulations often require backend investigation by Microsoft. Collecting the right diagnostic data accelerates the resolution process.

Because the Attack Simulation Training feature is a backend service managed by Microsoft Defender for Office 365, local troubleshooting is often limited. Documenting the specific failure points is crucial before engaging the official support channels.

Document the Error Environment

Record the exact error message displayed on the screen, the current environment, your deployment ID, and the specific version of the Microsoft 365 portal you are utilizing.

Note the Affected Settings

Write down the specific configuration of the malware-attachment attack simulation you were attempting to create, particularly around the Target Users and phishing landing page steps.

Open a Support Request

Navigate to the Microsoft 365 admin center, access the Support section, and create a new service request routed to the Microsoft 365 security team. Provide them with your collected diagnostic data.

Gather Error Details and Escalate to Microsoft Support

Community Collaboration: Once Microsoft provides a working resolution, consider documenting and sharing the fix in your local administrator knowledge base to help others facing the same loading issue.

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Frequently Asked Questions

Why does the phishing landing page selection screen fail to load?

This is typically caused by backend service interruptions, a corrupted browser cache, or temporary syncing issues within the Microsoft Defender portal.

What roles are required to manage Attack Simulation Training in M365?

You need to be assigned the Global Administrator, Security Administrator, or Attack Simulation Administrator role in Azure Active Directory to create and manage these simulations.

Can I bypass the client error by using a different browser?

Sometimes. Clearing your browser cache or switching to an InPrivate/Incognito window or a completely different browser (like Edge or Chrome) can help rule out local browser issues causing the client error.

Microsoft Office Security Issues