Windows error 8445 (ERROR_DS_DRA_BAD_INSTANCE

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Replication encountered an object with an invalid instance type.

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ERROR_DS_DRA_CONNECTION_FAILED	ERROR_DS_DRA_OUT_OF_MEM

ERROR_DS_DRA_BAD_INSTANCE_TYPE

ERROR_DS_DRA_BAD_INSTANCE_TYPE (8445) is an Active Directory replication error. An object involved in the replication transaction has instance-type state that is invalid for the receiving replica. The error is about replication metadata and replica role, not simply an object-property validation failure.

What to check

Record the object DN, its object GUID, and the naming context from the Directory Service log.
Compare object replication metadata between a known-good partner and the affected domain controller.
Check whether the issue followed a restore, forced demotion, interrupted decommission, or other topology change.

Useful command

repadmin /showobjmeta <DestinationDC> "<DistinguishedName>"

Microsoft: Diagnose AD replication failures · Microsoft: Lingering objects in an AD DS forest · Microsoft: Repadmin /showrepl

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