Event ID:304 Automatic registration failed at join phase.

WE have been seeing this on a Windows 2016 SQL server:

Log Name:      Microsoft-Windows-User Device Registration/Admin
Source:        Microsoft-Windows-User Device Registration
Date:          28/10/2019 10:11:10
Event ID:      304
Task Category: None
Level:         Error
Keywords:      
User:          SYSTEM
Computer:      server.domain.local
Description:
Automatic registration failed at join phase.  Exit code: Unknown HResult Error code: 0x801c001d. Server error: empty. Debug Output:\r\n joinMode: Join
drsInstance: undefined
registrationType: undefined
tenantType: undefined
tenantId: undefined
configLocation: undefined
errorPhase: discover
adalCorrelationId: undefined
adalLog: undefined
adalLog: undefined
adalResponseCode: 0x0
.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-User Device Registration" Guid="{23B8D46B-67DD-40A3-B636-D43E50552C6D}" />
    <EventID>304</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8000000000000000</Keywords>
    <TimeCreated SystemTime="2019-10-28T10:11:10.922655700Z" />
    <EventRecordID>36</EventRecordID>
    <Correlation />
    <Execution ProcessID="1420" ThreadID="356" />
    <Channel>Microsoft-Windows-User Device Registration/Admin</Channel>
    <Computer>server.domain.local</Computer>
    <Security UserID="S-1-5-18" />
  </System>
  <EventData>
    <Data Name="ExitCode">-2145648611</Data>
    <Data Name="ServerErrorMessage">empty</Data>
    <Data Name="TenantName">joinMode: Join
drsInstance: undefined
registrationType: undefined
tenantType: undefined
tenantId: undefined
configLocation: undefined
errorPhase: discover
adalCorrelationId: undefined
adalLog: undefined
adalLog: undefined
adalResponseCode: 0x0
</Data>
  </EventData>
</Event>

We are not using Azure or a Hybrid Environment, so can we ignore these?

Have a look here:

https://forum.sircles.net/posts/t1512-Automatic-registration-failed-at-join-phase---Exit-code--Unknown