A corruption was discovered in the file system structure

What it means

NTFS found damage on a volume.

Why it matters

Can lead to unreadable files or folders.

What to do

• Back up first.
• Run chkdsk /scan, then schedule chkdsk /f if errors are reported.
• Check the disk’s health (see events 7 and 153).

Find it with PowerShell

Get-WinEvent -MaxEvents 20 -FilterHashtable @{
  LogName = 'System'; Id = 55
} | 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.