ErrorFindly
0x00000128BSODCritical

0x00000128 — Worker Thread Returned with Bad IO Priority | Blue Screen Fix Guide

WORKER_THREAD_RETURNED_WITH_BAD_IO_PRIORITY

Windows XPWindows VistaWindows 7Windows 8Windows 10Windows 11

What Does 0x00000128 Mean?

A worker thread returned with an I/O priority that was different from what it started with.

Real-World Causes

  1. 1Driver work item changing I/O priority without restoring it
  2. 2Driver bug in worker thread callback

Symptoms

  • ⚠Blue screen with stop code WORKER_THREAD_RETURNED_WITH_BAD_IO_PRIORITY
  • ⚠System reboots unexpectedly
  • ⚠Possible data loss from unsaved work

DIY Fix

Beginner-friendly steps you can try at home

  1. 1Restart your computer
  2. 2Run System File Checker (sfc /scannow)
  3. 3Check Windows Update
  4. 4Run DISM /Online /Cleanup-Image /RestoreHealth

Advanced Fix

For experienced users and IT professionals

  1. 1Analyze minidump with WinDbg
  2. 2Check Event Viewer for correlated errors
  3. 3Use Process Monitor to trace system activity
  4. 4Perform clean boot to isolate the cause

Frequently Asked Questions

What causes WORKER_THREAD_RETURNED_WITH_BAD_IO_PRIORITY?
A worker thread returned with an I/O priority that was different from what it started with.
Can I fix Worker Thread Returned with Bad IO Priority myself?
In many cases yes. Start with basic troubleshooting like restarting, updating drivers, and running System File Checker. If the issue persists, advanced analysis of crash dumps may be needed.

Related Error Codes

0x00000129Worker Thread Returned with Bad Paging IO Priority0x000000E1Worker Thread Returned at Bad IRQL

About the Author

Windows Troubleshooting Team

Verified against official Microsoft documentation and real-world diagnostic data. Error behavior confirmed across Windows 10, Windows 11, and Windows Server.