WWindows RepairIntelligence™
Search
ToolsFavoritesHistoryLogin
Windows Repair Intelligence™ Report

0XC0000161

An illegal character was encountered. For a multibyte character set, this includes a lead byte without a succeeding trail byte. For the Unicode character set this includes the characters 0xFFFF and 0xFFFE

Home / Error Codes / Windows system operation / 0XC0000161

Microsoft defines 0XC0000161 as STATUS_ILLEGAL_CHARACTER: An illegal character was encountered. For a multibyte character set, this includes a lead byte without a succeeding trail byte. For the Unicode character set this includes the characters 0xFFFF and 0xFFFE.

SeverityMediumSystemsWindows 10 / 11SymbolSTATUS_ILLEGAL_CHARACTERUpdatedSep 1, 2026

Overview

0XC0000161 is the NTSTATUS representation of STATUS_ILLEGAL_CHARACTER. The code identifies the documented condition, while the calling program, timestamp, logs, and repeatable operation identify the responsible component.

Common causes

  • The affected operation returned the official STATUS_ILLEGAL_CHARACTER condition
  • The calling program encountered the documented result: An illegal character was encountered. For a multibyte character set, this includes a lead byte without a succeeding trail byte. For the Unicode character set this includes the characters 0xFFFF and 0xFFFE.
  • A configuration, resource, or dependency used by the windows system operation operation did not meet its requirements
  • A recent program, service, installer, or system change altered the context in which 0XC0000161 occurs

Symptoms

  • Confirm which operation returned 0XC0000161
  • Match 0XC0000161 to events from the same timestamp
  • Retest once and preserve any changed result

Prevention

  • Preserve Application and System events that accompany 0XC0000161
  • Use supported installers and configuration methods for the affected windows system operation workflow
  • Document changes so the operating context for STATUS_ILLEGAL_CHARACTER can be reconstructed

0XC0000161 diagnostic evidence

Official-definition grounded

Use the code identity and the affected operation together. The same numeric result can appear in different workflows, so logs and symptoms determine the safest repair branch.

Hexadecimal0XC0000161
Unsigned decimal3221225825
SymbolSTATUS_ILLEGAL_CHARACTER
Error familyWindows system operation
Severity bitFailure
Evidence sourceMicrosoft Open Specifications [MS-ERREF] NTSTATUS Values
1Confirm the operationConfirm which operation returned 0XC0000161
2Collect matching evidenceMatch 0XC0000161 to events from the same timestamp
3Retest the same actionRetest once and preserve any changed result

Definition source: Microsoft Open Specifications [MS-ERREF] NTSTATUS Values. This report preserves the official code identity and does not claim one universal cause.

How to troubleshoot error 0XC0000161

Use these Windows-native steps in order. Stop when Windows Update works again; advanced repair commands are not necessary on every PC.

1

Restart Windows and retry the update

Save your work, restart the PC, then open Settings > Windows Update and select Check for updates. A restart can release pending files without changing Windows configuration.

2

Run the Windows Update troubleshooter

Open Settings > System > Troubleshoot > Other troubleshooters. Locate Windows Update and select Run. Current Windows 11 versions may continue the diagnostic flow in Get Help.

3

Repair Windows components when indicated

If troubleshooting still reports missing or damaged components, open Terminal as administrator, run DISM RestoreHealth, and then run System File Checker. Do not interrupt either scan.

Before advanced repair: Back up important files. Managed work or school PCs may use organization update policies, so contact the administrator before changing services or update components.

Official-source grounding

The error meaning is grounded in Microsoft Open Specifications [MS-ERREF] NTSTATUS Values. The visual sequence also follows Microsoft Support guidance for Windows Update troubleshooting and Microsoft DISM repair guidance. Causes and repair steps vary by system evidence; this report does not claim a universal success rate.

Frequently asked questions

What does 0XC0000161 mean?

Microsoft defines 0XC0000161 as STATUS_ILLEGAL_CHARACTER: An illegal character was encountered. For a multibyte character set, this includes a lead byte without a succeeding trail byte. For the Unicode character set this includes the characters 0xFFFF and 0xFFFE. 0XC0000161 is the NTSTATUS representation of STATUS_ILLEGAL_CHARACTER. The code identifies the documented condition, while the calling program, timestamp, logs, and repeatable operation identify the responsible component.

Is 0XC0000161 always caused by the same problem?

No. The code identifies a failure condition, but the exact cause depends on the affected operation, Windows build, logs, and recent system changes.

Can Advanced System Repair help with 0XC0000161?

Advanced System Repair can scan for damaged Windows components and related system issues. No tool can guarantee one universal fix; preserve backups and match repair steps to the evidence on the affected PC.