Who is this article for?

Users who encounter greyed out buttons after seeing this error.

No elevated permissions are required.

This article walks you through how to troubleshoot the error you might see on startup.

1. Issue

Shortly after starting Outlook, the following error appears and the ribbon buttons remain disabled.

There are two possible causes:

1.1. Protection systems

This happens because Mail Manager modules are being prevented from running by protection systems.

This stops Outlook from spawning unknown child processes, in this example, the MailManager.Startup.exe.

1.2. Corrupt installation

This happens due to a corrupt installation of Mail Manager.

2. Solution

2.1. Protection systems

To resolve this issue, identify the system that would prevent Outlook from spawning child process and implement exceptions for files and folders located in the Mail Manager installation folder.

Using Microsoft Defender Attack Surface Reduction?
Follow steps outlined in our Configuring Attack Surface Reduction (ASR) article to resolve the error.

2.2. Corrupt installation

To resolve the issue, exit Outlook and reinstall Mail Manager.