NetWare Migration Wizard

Over the past month I have done 2 NetWare 4.11 – 5.1 migrations using the Migration Wizard. On both occasions I have hit the same problem when trying the last step (Finish NDS Migration). I get the following error:

Some of the files in the _Netware directory were not deleted
(Error code: 0X89fb Function Name: NWNCPExtensionRequest)

On one of the upgrades I was able to choose the Tools-Restore Trustees to Source option but this did not work on the other one (I used tbackup instead).

Does anyone know what causes these errors as I am doing another migration in a couple of weeks! Thanks…