Mac Error -600 — Process Not Found (procNotFound)

Mac error -600 occurs when the system tries to communicate with a process that no longer exists, common with crashing apps and Apple Event failures. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Error -600 maps to procNotFound — the target process for an Apple Event cannot be found. Apple Events are the inter-process communication mechanism in macOS. Occurs when an app crashes or quits while another app tries to communicate with it. Common with AppleScript, Automator, and apps that use inter-app communication. Launch Services database corruption can cause persistent -600 errors. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Target application crashed or was force-quit during Apple Event delivery. Launch Services database out of sync — app registered but not running. AppleScript trying to communicate with an app that is not open. Sandboxing restrictions blocking inter-process communication. Corrupted application bundle preventing proper process registration. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Open the target application manually before running the AppleScript or automation. Rebuild Launch Services database: /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user. Restart the Mac to clear stale process references. Check Console.app for crash logs related to the target application. Reinstall the application if crash logs show consistent failures. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Mac Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.