How can I interpret SDK error codes related to Windows Update Agent?

Overview

When using the Windows Update Agent (WUA) to execute GetMissingPatches, GetInstalledPatches, or InstallMissingPatches, it can be challenging to determine the cause of failure if these operations do not succeed. This article explains how to interpret the behavior and return codes of these methods.

Understanding the Interaction Between Windows Update Agent and SDK

The GetMissingPatches, GetInstalledPatches, and InstallMissingPatches methods act as wrappers around native Windows Update operations and are primarily used in compliance verification workflows. When a patch is passed to one of these methods, the system follows the standard behavior defined by Microsoft Windows Update.

To function correctly, the following conditions must be met:

• Windows Update must be enabled and allowed by system policy
• The Windows Update service must be running.
• Internet connectivity must be available.

The table below outlines common failure scenarios and their corresponding error codes:

If the Windows Update Agent is configured correctly, the following conditions may still lead to different behavior:

• Windows Update service startup type is set to Disabled: Returns error code -24 (WAAPI_ERROR_NOT_RUNNING).
• No internet connection available: Returns error code -17 (WAAPI_ERROR_NO_CONNECTION).
• Windows Update service is set to Manual, Automatic, Boot, or System, and internet connection is available: Returns the list of missing patches successfully.