Fix com.apple.launchd.peruser Error Crash Loop on macOS

Symptoms

• Repeated pop-up or notification: 'com.apple.launchd.peruser' quit unexpectedly.
• System becomes sluggish or unresponsive.
• High CPU usage by launchd or related processes.
• Crash reports in Console app showing launchd.peruser repeated crashes.
• Applications may fail to launch or behave erratically.

Root Causes

• Corrupted user-specific launch agents: Plist files in ~/Library/LaunchAgents that are malformed or incompatible.
• Third-party software: Applications that install faulty launch agents (e.g., outdated antivirus, system utilities).
• Incomplete macOS update: System files left in inconsistent state after an upgrade.
• User cache corruption: Cached data interfering with launchd operations.
• Permissions issues: Incorrect file permissions on user library folders.

Step-by-Step Fix

1. Identify the Problematic Launch Agent

1. Open Console app (from /Applications/Utilities).
2. Click on Crash Reports in the sidebar.
3. Look for reports named com.apple.launchd.peruser. Open the most recent one.
4. Scroll down to the Backtrace section. Note any references to specific plist files or bundle identifiers (e.g., com.thirdparty.agent).

2. Remove or Disable the Offending Agent

1. Open Terminal.
2. Navigate to user launch agents: cd ~/Library/LaunchAgents
3. List files: ls -la
4. If you identified a specific plist (e.g., com.thirdparty.agent.plist), remove it: rm com.thirdparty.agent.plist
5. If unsure, temporarily move all plist files to a backup folder:

   mkdir ~/Desktop/launchagents_backup
   mv *.plist ~/Desktop/launchagents_backup/

6. Reboot your Mac.

3. Clear User Cache and Temp Files

1. In Terminal, run:

   rm -rf ~/Library/Caches/*
   rm -rf ~/Library/Logs/*
   rm -rf ~/Library/Preferences/com.apple.launchd*

2. Empty Trash and reboot.

4. Repair Disk Permissions (if applicable)

1. For macOS Catalina and earlier: Boot into Recovery Mode (Cmd+R at startup), open Disk Utility, select your startup disk, and click First Aid.
2. For macOS Big Sur and later: Run in Terminal:

   sudo diskutil repairPermissions /

   Note: This command may not be available; use First Aid from Recovery instead.

5. Boot into Safe Mode

1. Restart your Mac and hold the Shift key immediately after the chime.
2. Release when you see the login window. Login (may require multiple attempts).
3. Safe Mode loads only essential kernel extensions and disables user launch agents.
4. If the crash does not occur in Safe Mode, the issue is with a third-party agent.
5. Reboot normally.

Alternative Fixes

• Create a new user account: If the crash persists, the user profile may be corrupted. Create a new admin account via System Settings > Users & Groups, and migrate data.
• Reset NVRAM/PRAM: For Intel Macs: Shut down, then press Option+Cmd+P+R at startup for 20 seconds.
• Reinstall macOS: As a last resort, reinstall macOS from Recovery Mode without erasing your data.

Prevention

• Regularly update macOS and third-party software.
• Avoid installing untrusted applications that modify launch agents.
• Periodically review ~/Library/LaunchAgents and remove unused plist files.
• Use tools like EtreCheck to monitor system integrity.
• Maintain regular backups with Time Machine.