⚠️ 2 verified solutions available for Error 1445 — Last updated 2026-03-22
Error 1445 📋

Fix ERROR_NON_MDICHILD_WINDOW — Windows Error Code 1445

Error 1445 (ERROR_NON_MDICHILD_WINDOW) is a Windows Security & Privileges error that occurs when cannot process a message from a window that is not a multiple document interface (mdi) window.. This guide provides step-by-step solutions to resolve this issue.

🏷️ Code: 1445 📛 ERROR_NON_MDICHILD_WINDOW 📅 Updated: 2026-03-22 ⏱️ 2 Solutions
⚡ Quick Fix

Run as Administrator: Right-click the application → 'Run as administrator'

👇 See all 2 solutions below
🐞 Auto-Fix Script for Error 1445
⚠️ How to use: Open PowerShell as Administrator, paste the code above, and press Enter.
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📑 Table of Contents
What is Error 1445? Common Causes Step-by-Step Solutions Prevention Tips Related Errors

💡 What is Error 1445?

Windows System Error Code 1445, known as ERROR_NON_MDICHILD_WINDOW, is a Security & Privileges error that occurs during security, authentication, and user privileges. The error indicates that: Cannot process a message from a window that is not a multiple document interface (MDI) window. When this error is encountered, the Windows operating system was unable to complete the requested operation within the security services subsystem. The error code 1445 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_NON_MDICHILD_WINDOW 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 security, authentication, and user privileges is essential for effective troubleshooting.

⚠️ Common Causes

  • System resource conflict: Cannot process a message from a window that is not a multiple document interface (MDI) window.
  • User account lacks required permissions
  • Group Policy restricts access
  • Authentication credentials expired
📚 Comprehensive Guide

Mastering SFC and DISM: The Complete System Repair Guide

An in-depth encyclopedia on successfully repairing corrupted Windows image files and system components using SFC and DISM command line tools.

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✅ Step-by-Step Solutions

1 Run as Administrator
  1. Right-click the application → 'Run as administrator'
  2. If Error 1445 (ERROR_NON_MDICHILD_WINDOW) resolves, it's a permissions issue
  3. For permanent fix, right-click → Properties → Compatibility → check 'Run as administrator'
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2 Check User Account Permissions
  1. Open Computer Management (compmgmt.msc)
  2. Navigate to Local Users and Groups → Users
  3. Verify your account is in the Administrators group
  4. If not, add it and log off/on

🎬 Video Tutorials

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How to fix Error 1445 (Non Mdichild Window)
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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 "*1445*" -or $_.Message -like "*ERROR_NON_MDICHILD_WINDOW*"} | Format-List

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

🛡️ Prevention Tips

  • Apply least-privilege principle
  • Audit user accounts regularly
  • Keep security policies and AV updated
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Last updated: 2026-03-22
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Based on Official Microsoft Documentation
Solutions Tested on Windows 10 & 11
Error codes sourced from Microsoft Win32 SDK. Updated 2026-03-22.
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