How to fix Error 545 on Windows 11

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Windows 11 Error 545: Invalid Object/Port Attributes for NtCreatePort/NtConnectPort

Why This Error Happens

Error 545 occurs when the Local Procedure Call (LPC/ALPC) subsystem receives malformed or inconsistent attribute structures while attempting to create or connect to a system port. This typically stems from corrupted system files, a damaged Windows registry affecting the Security Reference Monitor or Session Manager, or third-party security software intercepting and improperly modifying inter-process communication calls. In rare cases, it can also result from incompatible or outdated drivers interfering with kernel-level object management.

Step-by-Step Resolution Guide

  1. Run System File Checker (SFC) and DISM
    Open Command Prompt as Administrator and execute:
   sfc /scannow
   DISM /Online /Cleanup-Image /RestoreHealth

Restart your computer once both scans complete.

  1. Check for Conflicting Security Software
    Temporarily disable third-party antivirus or endpoint protection tools (via their system tray icon or Settings > Apps > Installed Apps). If the error disappears, uninstall and reinstall the security software, or switch to Windows Defender temporarily to isolate the conflict.

  2. Update or Roll Back Device Drivers
    Open Device Manager (Win + X > Device Manager), focus on Display, Storage Controller, and Network adapters. Right-click each, select Update Driver. If the error began after a recent driver update, instead select Properties > Driver tab > Roll Back Driver.

  3. Inspect Windows Event Viewer for Correlating Errors
    Open Event Viewer > Windows Logs > System, filter for Error/Warning events around the same timestamp as Error 545. Note any related Service Control Manager or Kernel-General events, as these often reveal the specific process or driver triggering the invalid port attributes.

  4. Perform a Clean Boot to Isolate Startup Conflicts
    Run msconfig, go to the Services tab, check Hide all Microsoft services, then click Disable all. Restart and monitor whether Error 545 recurs. Re-enable services one by one to identify the culprit.

Alternative or Verification Steps

  • Verify the fix: Reproduce the original action that triggered Error 545 (e.g., launching the specific application) and confirm the error no longer appears in Event Viewer under Windows Logs > System.
  • Alternative fix: If the issue persists, use System Restore (rstrui.exe) to revert to a restore point predating the error, or consider an in-place upgrade repair via Windows 11 installation media to fix deep system corruption without losing files.