⚠️ 2 verified solutions available for Error 5021 — Last updated 2026-04-05
Error 5021 📋

Fix ERROR_NOT_QUORUM_CAPABLE — Windows Error Code 5021

Error 5021 (ERROR_NOT_QUORUM_CAPABLE) is a Windows DNS & WINS error that occurs when the cluster could not make the specified resource a quorum resource because it is not capable of being a quorum resource.. This guide provides step-by-step solutions to resolve this issue.

🏷️ Code: 5021 📛 ERROR_NOT_QUORUM_CAPABLE 📅 Updated: 2026-04-05 ⏱️ 2 Solutions
⚡ Quick Fix

Flush DNS and Switch Servers: Open Command Prompt as Administrator

👇 See all 2 solutions below
🐞 Auto-Fix Script for Error 5021
⚠️ How to use: Open PowerShell as Administrator, paste the code above, and press Enter.
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📑 Table of Contents
What is Error 5021? Common Causes Step-by-Step Solutions Prevention Tips Related Errors

💡 What is Error 5021?

Windows System Error Code 5021, known as ERROR_NOT_QUORUM_CAPABLE, is a DNS & WINS error that occurs during DNS resolution and WINS name resolution. The error indicates that: The cluster could not make the specified resource a quorum resource because it is not capable of being a quorum resource. When this error is encountered, the Windows operating system was unable to complete the requested operation within the DNS/WINS services subsystem. The error code 5021 is returned by the GetLastError() function and provides developers with a specific identifier to diagnose the root cause of the failure. The symbolic name ERROR_NOT_QUORUM_CAPABLE maps directly to this numeric code and is commonly referenced in Microsoft documentation, developer forums, and system logs. Understanding this error and its context within DNS resolution and WINS name resolution is essential for effective troubleshooting.

⚠️ Common Causes

  • System resource conflict: The cluster could not make the specified resource a quorum resource because it is not capable of being a quorum resource.
  • DNS server misconfigured
  • Stale DNS cache entries
  • Hostname cannot be resolved
📚 Comprehensive Guide

Understanding HRESULT Codes: A Deep Dive into Windows Error Architecture

A deep technical dive into decoding 32-bit HRESULT error codes in Windows, understanding facility codes, and identifying error sources.

Read the full guide →

✅ Step-by-Step Solutions

1 Flush DNS and Switch Servers
  1. Open Command Prompt as Administrator
  2. Run: ipconfig /flushdns
  3. Change DNS to Google (8.8.8.8) or Cloudflare (1.1.1.1)
  4. Run: ipconfig /registerdns
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2 Advanced Diagnostic for ERROR_NOT_QUORUM_CAPABLE
  1. Open Windows Event Viewer (eventvwr.msc)
  2. Navigate to Windows Logs → System to find Event ID 5021
  3. Look for associated warnings that occurred immediately before the system crashed
  4. Right-click the entry and export the log file for further analysis

🎬 Video Tutorials

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How to fix Error 5021 (Not Quorum Capable)
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💻 Diagnostic Command

Run this PowerShell command to find related events in your system log:

Get-EventLog -LogName System -Newest 20 | Where-Object {$_.Message -like "*5021*" -or $_.Message -like "*ERROR_NOT_QUORUM_CAPABLE*"} | Format-List

💡 Open PowerShell as Administrator, paste the command above, and press Enter.

🛡️ Prevention Tips

  • Use reliable DNS (8.8.8.8 or 1.1.1.1)
  • Flush DNS cache periodically
  • Monitor DNS resolution performance
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Last updated: 2026-04-05
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Based on Official Microsoft Documentation
Solutions Tested on Windows 10 & 11
Error codes sourced from Microsoft Win32 SDK. Updated 2026-04-05.
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