Event ID 551: Storport Device (Port = …, Path = …, Target = …, Lun = …) was surprise removed
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.
Storport Device (Port = …, Path = …, Target = …, Lun = …) was surprise removed.
Corresponding Class Disk Device Guid is ….
SMB Session Authentication Failure
Event 551
SMBServer
SMBServer/Operational log
Error
Message and fields (as Event Viewer shows them)
SMB Session Authentication Failure
Client Name: …
Client Address: …
User Name: …
Session ID: …
Status: … (…)
SPN: …
SPN Validation Policy: …
Guidance:
You should expect this error when attempting to connect to shares using incorrect credentials.
This error does not always indicate a problem with authorization, but mainly authentication. It is more common with non-Windows clients.
This error can occur when using incorrect usernames and passwords with NTLM, mismatched LmCompatibility settings between client and server, an incorrect service principal name, duplicate Kerberos service principal names, incorrect Kerberos ticket-granting service tickets, or Guest accounts without Guest access enabled