Stop-DbaProcess - Skip system sessions instead of trying to kill them

[andreasjordan]

Summary

Stop-DbaProcess called KillProcess for every session Get-DbaProcess returned, system sessions included. SQL Server refuses those with "Only user processes can be killed", so each of them ended in a Couldn't kill spid N warning, and that warning reaches the caller's -WarningVariable even through -WarningAction SilentlyContinue.

Until SQL Server 2022 this was mostly invisible, because system sessions sat below spid 50 and in master, where nobody aims a Stop-DbaProcess -Database at them. SQL Server 2025 parks system workers such as the "DB MIRROR" tasks above spid 50 and in user databases. On the lab's clustered SQL Server 2025 instance (FCI01) a "DB MIRROR" worker born by a mirroring test stayed in whatever user database was current, and from then on every restore of an existing database (Invoke-DbaAdvancedRestore kills the sessions of the database first, with -WarningAction SilentlyContinue) and every test that clears the sessions of its database before dropping it got the warning: Restore-DbaDatabase.Tests.ps1 failed three $WarnVar | Should -BeNullOrEmpty assertions and Set-DbaDbCompression.Tests.ps1 failed its AfterAll under EnableException.

Get-DbaProcess already reports IsSystem, which matches is_user_process = 0 (checked on FCI01: the 29 system sessions above spid 50 are exactly the sessions with IsSystem = True). Stop-DbaProcess now skips those with a verbose message, the way it already skips its own spid. Nothing changes for user sessions, and the callers in Invoke-DbaAdvancedRestore need no change: the ALTER DATABASE ... WITH ROLLBACK IMMEDIATE that follows the kill handles whatever is left.

Test plan

• New Context in Stop-DbaProcess.Tests.ps1: a system session of the instance piped in and selected by -Spid produces no output and no warning. Every instance has system sessions, so this runs on every lane.
• Red on old: both new tests fail on development with the Couldn't kill spid warning in $WarnVar.
• Lab, with the DB MIRROR worker still parked on FCI01: Restore-DbaDatabase.Tests.ps1 and Set-DbaDbCompression.Tests.ps1 under the FCI configuration on PowerShell 7 (the two files that reproduced the failure alone).
• Stop-DbaProcess.Tests.ps1 green on PowerShell 7 and Windows PowerShell 5.1.

created by Claude and reviewed by Andreas Jordan

🤖 Generated with Claude Code

[potatoqualitee]

Reviewed the complete command and test changes at this exact head, including system-session classification, pipeline and explicit-SPID paths, callers, discussions, and passing integration CI. No material defects found.

[potatoqualitee]

merci 🙏🏼