Sam user unknown ex

Question

Please help! We are migrating our server to Windows Server 2019 with new hardware. The server is domain controller, DNS host and active directory host. Most but not all users cannot log in. I turned on debug with nltest and the log shows the subject message for the user "Sam user unknown ex" as if it can't resolve the client machine name and user. I suspect a DNS server problem but don't know what to do. The clients are windows 10 pro. Thanks!

Answer 1

Hi Lindsey-4821,

The two prerequisites to introducing your first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR. You can see information regarding this in the link below:

https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405

Go ahead and use dcdiag / repadmin tools to verify the health of the DC, correcting all errors found before starting any operations. Then:

Stand up the new 2019
Patch it fully
License it
Join existing domain
Add active directory domain services,
Promote it also making it a GC (recommended)
Transfer FSMO roles over (optional),
Transfer pdc emulator role (optional),

Use dcdiag / repadmin tools to again verify health, when all is good you can decommission / demote old your old server.

I hope this answers your question.

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