Windows Defender Full Scan Stops

Hi kirbster 1, 

I know how confusing it is to see your scan suddenly stops. Based on the details and screenshots you provided, the Defender engine actually crashed. The code (c0000005) and module (mpengine.dll) combination often points to an access violation, which aligns more with an engine issue than something wrong on your system.

Although I haven't found any similar reports yet, this might point to a Defender engine regression (which is not unusual on Insider builds) or corrupted definitions. First, let's verify if it is reproducible:

1. Run another Full scan:
2. If it works, this might be just one-off crash.
3. If it crashes again, continue with the check below:
   • Make sure everything is up to date:
     • Open Windows Security > Virus & threat protection > Protection updates > Check for updates
     • Then Settings > Windows Update > Check for updates > Advanced options > Optional updates
   • Reset Defender engine
     • Open Command Prompt (Admin) then run the commands below one by one
     • "%ProgramFiles%\Windows Defender\MpCmdRun.exe" -RemoveDefinitions -All
     • "%ProgramFiles%\Windows Defender\MpCmdRun.exe" -SignatureUpdate
   • Restart your PC after and check the scan again.

If still happening, this might be tied to preview regressions in the Defender platform or engine, since you’re on an Insider build. The next step would be reporting this via Feedback Hub (pressing Win + F).

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