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0XC00000EC

If an MM error that is not defined in the standard FsRtl filter is returned, it is converted to one of the following errors, which are guaranteed to be in the filter. In this case, information is lost; however, the filter correctly handles the exception

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Microsoft defines 0XC00000EC as STATUS_UNEXPECTED_MM_EXTEND_ERR: If an MM error that is not defined in the standard FsRtl filter is returned, it is converted to one of the following errors, which are guaranteed to be in the filter. In this case, information is lost; however, the filter correctly handles the exception.

SeverityMediumSystemsWindows 10 / 11SymbolSTATUS_UNEXPECTED_MM_EXTEND_ERRUpdatedSep 1, 2026

Overview

0XC00000EC is the NTSTATUS representation of STATUS_UNEXPECTED_MM_EXTEND_ERR. 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_UNEXPECTED_MM_EXTEND_ERR condition
  • The calling program encountered the documented result: If an MM error that is not defined in the standard FsRtl filter is returned, it is converted to one of the following errors, which are guaranteed to be in the filter. In this case, information is lost; however, the filter correctly handles the exception.
  • 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 0XC00000EC occurs

Symptoms

  • Confirm which operation returned 0XC00000EC
  • Match 0XC00000EC to events from the same timestamp
  • Retest once and preserve any changed result

Prevention

  • Preserve Application and System events that accompany 0XC00000EC
  • Use supported installers and configuration methods for the affected windows system operation workflow
  • Document changes so the operating context for STATUS_UNEXPECTED_MM_EXTEND_ERR can be reconstructed

0XC00000EC 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.

Hexadecimal0XC00000EC
Unsigned decimal3221225708
SymbolSTATUS_UNEXPECTED_MM_EXTEND_ERR
Error familyWindows system operation
Severity bitFailure
Evidence sourceMicrosoft Open Specifications [MS-ERREF] NTSTATUS Values
1Confirm the operationConfirm which operation returned 0XC00000EC
2Collect matching evidenceMatch 0XC00000EC 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 0XC00000EC

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 0XC00000EC mean?

Microsoft defines 0XC00000EC as STATUS_UNEXPECTED_MM_EXTEND_ERR: If an MM error that is not defined in the standard FsRtl filter is returned, it is converted to one of the following errors, which are guaranteed to be in the filter. In this case, information is lost; however, the filter correctly handles the exception. 0XC00000EC is the NTSTATUS representation of STATUS_UNEXPECTED_MM_EXTEND_ERR. The code identifies the documented condition, while the calling program, timestamp, logs, and repeatable operation identify the responsible component.

Is 0XC00000EC 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 0XC00000EC?

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.