When a client migrates from a Windows 2000 domain to another Windows 2000 domain using ADMT (Active Directory Migration Tool), the migration log may contain:

E26126: Failed to move object CN=<UserName>, hr=800720e4 The naming context could not be found.

When you trace the error, you receive:

LDAP: ProtocolOp: ModifyDNResponse (13)                              LDAP: ProtocolOp = ModifyDNResponse                              LDAP: Result Code = Unwilling to Perform                              LDAP: Error Message = 000020E4: SvcErr: DSID-031B02E2, problem 5003 (WILL_NOT_PERFORM)
This behavior occurs because the domain names in the parent domain of a parent or child domain relationship are in all capital letters. ADMT won't let you specify lower case domain names.

To workaround this behavior, specify lower case domain names Using the MoveTree utility to move objects between domains in a forest?