The warning "Your system has run out of application memory" appears with a Force Quit window listing your open apps. It means macOS has used up both its physical memory and the extra space it can borrow from your disk, and it needs you to close something.
What is happening
Your Mac keeps active apps in memory (RAM). When memory is full, macOS first compresses data in memory, then moves less-used data to swap files on your startup disk. This is slower than memory but keeps things running.
The warning appears when swap cannot grow any further. That usually happens for one of two reasons:
- An app is using far more memory than it should, often because of a bug (a "memory leak") or a very heavy workload, such as hundreds of browser tabs.
- Your startup disk is nearly full, so there is no room for swap files.
Fix it right now
- In the Force Quit window, look at the memory listed next to each app. Apps using an unusually large amount are highlighted.
- Switch to those apps and save your work if you can.
- Select the app and click Force Quit, or quit it normally.
- When things have settled, restart your Mac. This clears swap files and gives you a fresh start.
Find the cause
Open Activity Monitor and click the Memory tab.
- Sort by the Memory column. Watch over a few minutes: an app whose memory keeps climbing while you are not doing anything is a likely leak.
- Check Swap Used at the bottom. A few gigabytes is normal; a figure that keeps growing means memory is regularly running out.
- Check the Memory Pressure graph. If it is often yellow or red, your workload may be too heavy for the memory you have.
Browsers are the most common cause. Each tab and extension runs as its own process. Close tabs you do not need and remove extensions you do not use. See speeding up Safari and Chrome.
Free up disk space
Because swap lives on your startup disk, a nearly full disk makes this warning far more likely. Aim to keep at least 10 to 20 percent of your disk free. Start with freeing up storage on your Mac.
Update the app
If one app causes the warning repeatedly, check for an update. Memory leaks are bugs, and developers fix them. If an update does not help, contact the developer with details of what you were doing.
Reduce the load
- Avoid running several heavy apps at once, such as a video editor, a virtual machine and a browser with many tabs.
- Remove unnecessary login items so fewer apps run in the background. See stopping apps opening at startup.
- In Chrome, turn on Memory Saver in Settings > Performance.
When it is the hardware
If you see this warning often even with only a few apps open, and you have plenty of free disk space, your Mac may simply not have enough memory for your work. Memory in modern Macs cannot be upgraded, so the long-term fix is a Mac with more memory.
Frequently asked questions
What does “Your system has run out of application memory” mean?
macOS has filled both its RAM and the swap space it uses on your disk, and needs you to quit an app. It is usually caused by one app using too much memory or a nearly full startup disk.
Can low storage cause memory problems on a Mac?
Yes. macOS uses free disk space for swap files when RAM is full. If your disk is nearly full, there is no room for swap and memory warnings appear much sooner.
Should I use a RAM cleaner app?
No. macOS manages memory itself. RAM cleaners force data out of memory that macOS then has to load again, which usually makes things slower.
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