Microsoft-Windows-User Device Registration/Admin, Event-ID 304

Log Name	Microsoft-Windows-User Device Registration/Admin
Source	User Device Registration
Event-ID	304
Level	Error
User	SYSTEM
Task Category	None
Message	Automatic registration failed at join phase. Exit code: Unknown HResult Error code: 0x801c03f2 Server error: The device object by the given id (xxxxxxxxxxxx) is not found. Tenant type: Federated Registration type: fallback_sync Debug Output: joinMode: Join drsInstance: azure registrationType: fallback_sync tenantType: Federated tenantId: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx configLocation: undefined errorPhase: join adalCorrelationId: undefined adalLog: undefined adalResponseCode: 0x0

Check Registry-Key

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WorkplaceJoin

autoWorkplaceJoin     REG_DWORD     0x00000000 (0)

autoWorkPlaceJoin should be 0. If not change it. But be aware that your company maybe want to Azure-Join your computer.

Check group-policy

Start --> Run --> rsop.msc [Enter]
Computer Configuration > Policies > Administrative Templates > Windows Components > Device Registration >  Register domain joined computer as device => [Not configured]

You need to run rsop.msc as administrator. If the policy is [not configure] everything is alright. Otherwise your company maybe wants to register your computer in Azure.

Start --> Run --> gpedit.msc [Enter]
 
Computer Configuration > Policies > Administrative Templates > Windows Components > Device Registration >  Register domain joined computer as device => [Not configured] 

If the policy settings isn’t [Not configure] a local Administrator may have set it.

Check Scheduled Task

Open:

Task Scheduler Library\Microsoft\Windows\Workplace Join

There is a task:

"Automatic-Device-Join" or "Automatic-Workplace-Join"

Set it to disabled. But be aware that management systems like System Center Configuration Manager can trigger the task.

On your private computer you can delete the task.