Exchange Server Authentication Failure Bad GPO

Had an issue with Exchange 2016 CU14 not allowing users to login, but administrators could login just fine.

Turns out the policies on the server were corrupted, and a full reset needed to be done to fix the issue.

Move Exchange Computer account to OU with Blocking Inherritance

RUN: RD /S /Q “%WinDir%\System32\GroupPolicyUsers”
RUN: RD /S /Q “%WinDir%\System32\GroupPolicy”
RUN: GPupdate /force
RUN: secedit /configure /cfg %windir%\inf\defltbase.inf /db defltbase.sdb /verbose

TEST you can connect to OWA ECP Outlook…  it should work 🙂

Move your Exchange server Back to its normal out, then execute “gpupdate /force”

Confirm it still works, if not fix your Group Policies.

Maybe its this problem?

1.Click on Start/Run type secpol.msc.

2.Click OK

3.Expand Local Policies -> Click on User Rights Assignment

4.In the right pane double click Access this computer from the network.

5.Click Add user or Group ->Type in Authenticated Users (by default only Administrators is entered)

6.Click Ok -> Click Ok

That should do it. You may need to reboot.