What does Windows error code 14022 (ERROR_SXS_DUPLICATE_WINDOWCLASS_NAME) mean?

ERROR_SXS_DUPLICATE_WINDOWCLASS_NAME

ERROR_SXS_DUPLICATE_WINDOWCLASS_NAME means that more than one active side-by-side component contributes the same window-class name. The activation context cannot expose both registrations without ambiguity.

Inspect the active manifests that register the same class and determine which component should own it. Rename or isolate conflicting registrations through assembly design instead of relying on activation order to choose a window class.

What to check

• Identify the two assembly manifests that define the same window-class entry.
• Consolidate the registration into one component or give independently owned classes distinct names.
• Review private assemblies introduced by plug-ins or optional modules, which can add duplicate registrations indirectly.

The fix is to remove the conflicting manifest registrations, not to change ordinary runtime window creation calls.

Microsoft: side-by-side assemblies