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  3. setupact.log
LogRisk: Safe

setupact.log C:\Windows\setupact.log

Secondary log of setup component actions at the root of C:\Windows; the main Setup log is Panther\setupact.log.

Updated on By AltF4 Formation

What it’s for

C:\Windows\setupact.log is an action log from Windows setup components, written directly at the root of C:\Windows. Do not confuse it with C:\Windows\Panther\setupact.log, the main Setup log and the first one to open. The Panther log follows an installation or upgrade from start to finish, while the one at the root is a secondary log, usually short. Its error counterpart is setuperr.log, in the same folder.

What it contains

  • Timestamped setup action lines, with their level (Info, Warning, Error) and the emitting component.
  • The matching errors are isolated in setuperr.log, in the same location.

Risks and best practices

  • The file has no effect on how Windows runs. You can delete it, but you lose the installation trace.
  • To diagnose an installation or upgrade, start with the logs in the Panther folder.
  • It may cite computer names and paths, so review it before sending it to a third party.

Useful commands

Fenêtre de terminal
# File size and date
Get-Item "$env:windir\setupact.log" | Select-Object FullName, Length, LastWriteTime


# Last lines
Get-Content "$env:windir\setupact.log" -Tail 50


# Error lines
Select-String -Path "$env:windir\setupact.log" -Pattern 'Error|Failed' | Select-Object -Last 30

Format

Text file. Each line starts with the date and time, followed by the level (Info, Warning, Error), the emitting component and the message.

Rotation and archiving

The file is written during installation and then kept as it is.

How to read it

Look for Error or Failed lines, scroll up a few dozen lines to find the action involved, then cross-check with setuperr.log and Panther\setupact.log.

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