⚠️ 2 verified solutions available for Error 15021 — Last updated 2026-03-06
Error 15021 📋

Fix ERROR_EVT_FILTER_UNEXPECTEDTOKEN — Windows Error Code 15021

Error 15021 (ERROR_EVT_FILTER_UNEXPECTEDTOKEN) is a Windows Internet & WinHTTP error that occurs when the token encountered was unexpected.. This guide provides step-by-step solutions to resolve this issue.

🏷️ Code: 15021 📛 ERROR_EVT_FILTER_UNEXPECTEDTOKEN 📅 Updated: 2026-03-06 ⏱️ 2 Solutions
⚡ Quick Fix

Reset Internet Settings: Open Command Prompt as Administrator

👇 See all 2 solutions below
🐞 Auto-Fix Script for Error 15021
⚠️ How to use: Open PowerShell as Administrator, paste the code above, and press Enter.
✓ Safe & Transparent ✓ No Downloads Required ✓ Review Before Running
📑 Table of Contents
What is Error 15021? Common Causes Step-by-Step Solutions Prevention Tips Related Errors

💡 What is Error 15021?

Windows System Error Code 15021, known as ERROR_EVT_FILTER_UNEXPECTEDTOKEN, is a Internet & WinHTTP error that occurs during WinHTTP, WinInet, and internet protocols. The error indicates that: The token encountered was unexpected. When this error is encountered, the Windows operating system was unable to complete the requested operation within the internet services subsystem. The error code 15021 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_EVT_FILTER_UNEXPECTEDTOKEN 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 WinHTTP, WinInet, and internet protocols is essential for effective troubleshooting.

⚠️ Common Causes

  • System resource conflict: The token encountered was unexpected.
  • Proxy misconfigured
  • SSL/TLS handshake failure
  • Client certificate expired
📚 Comprehensive Guide

Diagnosing Memory Management and RAM Faults in Windows 10 & 11

An encyclopedia on diagnosing physical RAM defects, virtual memory (paging file) corruption, and resolving MEMORY_MANAGEMENT BSODs.

Read the full guide →

✅ Step-by-Step Solutions

1 Reset Internet Settings
  1. Open Command Prompt as Administrator
  2. Run: netsh winhttp reset proxy
  3. Open Internet Options → Advanced → Reset
  4. Restart your browser and applications
Advertisement
[AdSense In-Article Ad Generator]
Show Advanced Solutions (1 more)
2 Advanced Diagnostic for ERROR_EVT_FILTER_UNEXPECTEDTOKEN
  1. Open Windows Event Viewer (eventvwr.msc)
  2. Navigate to Windows Logs → System to find Event ID 15021
  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

▶️ Watch Video Tutorials
How to fix Error 15021 (Evt Filter Unexpectedtoken)
Open on YouTube →

💻 Diagnostic Command

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

Get-EventLog -LogName System -Newest 20 | Where-Object {$_.Message -like "*15021*" -or $_.Message -like "*ERROR_EVT_FILTER_UNEXPECTEDTOKEN*"} | Format-List

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

🛡️ Prevention Tips

  • Use centralized proxy management
  • Keep root certificates updated
  • Disable legacy SSL 3.0 protocol
Was this helpful?
Last updated: 2026-03-06
📖
Based on Official Microsoft Documentation
Solutions Tested on Windows 10 & 11
Error codes sourced from Microsoft Win32 SDK. Updated 2026-03-06.
🔧 Diagnose Your Error