Hello. On some machines, about half of 7 in place, with Win10 1809 installed on Server 2016 domain accessing on-site Exchange 2016, a user will create every couple of seconds (sometimes with gaps) on the Server 2016 DC 4776 and 4771 login failures involving error code 0xC000006A / Failure code 0x18 – Type 2 whenever Outlook 2019 is active on the client (we are strictly on-site setup, with no MS365 services enabled).
What I’ve discovered so far:
- Client Machines were installed about a month ago, on brand new Dell Latitude running Win10 1809;
- Accessing other network devices from a user / client doesn’t result in any login / authentication errors being reported;
- If a person is “susceptible” to the above (and different users come and go), starting up Outlook 2019 starts the authentication failures alerts being recorded;
- A susceptible person authentication failure alerts immediately stop once they’re done for the day;
- Appears to be triggered after a regular password reset, though not consistent;
- The susceptible person isn’t aware there is an issue, and is able to work without any interruptions;
- There are no Event log entries recorded on the Win10 client;
- On one Outlook setup with multiple mailboxes, something happens that results in the person being locked out, but so this behaviour is only observed with the one person;
- Using Netwrix Lockout tool hasn’t given me any additional insight as to what could be causing the above.
- On Win10 1803, we do see the following behaviour with Outlook 2019 that has been in place since January 2019:
On occasion a Microsoft window will pop up that originates from Microsoft.AAD.BrokerPlugin.exe that asks for a login name / pasword;
- Trying to enter correct credentials results in an incorrect password message (regardless of the account type);
- Closing this window, then clicking on Outlook’s “Need Password” prompt at the bottom right border, results in Outlook connecting to the Exchange server;
- On the one person running Win10 1809 with occasionally being locked out, they’re prompted with the “Need Password” a couple of times per day (possibly when they dock / undock their workstation);
- Both the Win 10 1803 and Win 10 1809 examples, each user has access to multiple mailboxes (about 4).
- I’m aware about the “Outlook bypasses AutoDiscover” registry fix, which I’ve not tried yet, as I’m not sure if this is the same issue as what I’m describing above.
Any assistance would be appreciated in further diagnosing or getting the root cause of the issue.
Thank you,
IT Manager Geek
