Not Responding

Give it a minute if it was doing something large, like opening a big file. If it does not recover, press Option-Command-Esc, select the app, and click Force Quit. The Force Quit window also marks unresponsive apps.

Before you force quit, you can capture a sample in Activity Monitor (More > Sample Process) to send to the developer.

Check for an update to the app. If it happens with many apps, look at memory pressure, free disk space, and which processes use the most CPU in Activity Monitor. Restarting the Mac clears most temporary causes.

The Force Quit window only lists apps. Activity Monitor also shows background processes that have stopped responding.

1. Press Option-Command-Esc. The Force Quit window marks unresponsive apps with (Not Responding).
2. For background processes too, open Activity Monitor and choose View > All Processes.
3. Look for names in red with (Not Responding). Click the Process Name header to sort if the list is long.
4. Double-click the process to open its info window. The Parent Process field shows which app or service started it.

An app is marked Not Responding when its main thread stops handling events. These are the usual reasons.

If several apps are Not Responding at the same time, the cause is usually something they share, such as memory pressure, a full disk, or a network drive that went away. If it is always the same app, the cause is more likely inside that app.

• It is working on a large file or task and has not finished yet.
• It is waiting on a network server, a network drive, or an external disk.
• It is waiting on another process, such as a plug-in, an extension, or a system service.
• The Mac is under high memory pressure, so the app is slowed by swapping.
• The startup disk is nearly full.
• A bug in the app, often tied to one file, one plug-in, or one setting.

If the app holds work you care about, take a minute before ending it.

1. Wait. Watch its % CPU in Activity Monitor. A busy app may be making progress.
2. Select it and choose More > Sample Process, then save the report. This is what a developer needs to find the cause.
3. Choose Quit first. Use Force Quit only if Quit does not work.
4. After you reopen the app, check whether it offers to restore your windows or documents.

When an unresponsive app is force quit, macOS can save a report in /Library/Logs/DiagnosticReports. Open the Console app in Applications > Utilities, and look under Reports in the sidebar at Spin Reports and Diagnostic Reports. Reports named after the same app on different days show a pattern worth sending to its developer.