The session setup from a computer failed to authenticate

What it means

Logged on a domain controller when a computer’s machine account password doesn’t match (a broken trust relationship).

Why it matters

That computer will show "The trust relationship between this workstation and the primary domain failed".

What to do

• Repair with Test-ComputerSecureChannel -Repair on the affected computer.
• Or rejoin the computer to the domain.

Find it with PowerShell

Get-WinEvent -MaxEvents 20 -FilterHashtable @{
  LogName = 'System'; Id = 5805
} | Select-Object TimeCreated, ProviderName, Message

Add -ComputerName SERVER to query another machine. Other event sources can reuse the same ID number, so check the ProviderName column.