Event ID 204: RegisterEventSource legacy API was used to register
Windows Event ID Lookup: What Windows event IDs mean: 4625, 4624, 4740, 6008, 41, 7045, 1102 and 3,000 more, with Windows' own message text, the fields and what to check.
Look up a Windows event ID from Event Viewer, a SIEM alert or a log export: what it means, the fields it records, and what to check. Many IDs are used by more than one source (event 41 is both a Kernel-Power crash and a boot error), so every definition is shown, the one people usually mean first. The message text is Windows' own, read from the event providers of Windows 10.0.26200.0, 2026-10-28; the notes are ours, based on Microsoft's security auditing reference.
RegisterEventSource legacy API was used to register
Event 204
Eventlog
Security / System log
Verbose
The TPM was found not to be useable for BitLocker.
Event 204
Kernel-Boot
System log
Error
CleanCheckpointStart VolumeId: …, Reason: …, Usage: …%
Event 204
Ntfs
System log
Information
Dispatching a read request.
Event 204
StorPort
System log
Information
Kerberos does not accept PKINIT KDC replies using public key encryption.
Event 204
Security-Kerberos
System log
Warning
OS Loader Start
Event 204
Kernel-PnP
System log
Information
Task Scheduler failed to retrieve the event triggering values for task "…" .
Event 204
TaskScheduler
TaskScheduler/Operational log
Error
SMB2 Work Item external activity id stop
Event 204
SMBServer
SMBServer/Operational log
Information
The BITS service provided job credentials in response to the … authentication challenge from the … server for the … transfer job that is associated with the following URL
Event 204
Bits-Client
Bits-Client/Operational log
Error