"Your system has run out of application memory": what to do
· 6 min read
The Force Quit Applications window opens on its own and says “Your system has run out of application memory.” macOS has filled its working memory and the swap space on disk behind it, so it has started pausing apps to keep the Mac usable. The cause is nearly always one of two things: one app whose memory keeps growing, or a startup disk too full for swap to grow. Quit one app now, then find out which of the two you have.
What the warning is telling you
A Mac juggles memory in three layers. Apps use RAM first. When RAM runs short, macOS compresses memory that hasn’t been touched for a while. When that isn’t enough, it moves some of it out to the startup disk as swap, in files it keeps in /System/Volumes/VM and adds to as the need grows.
The warning appears when all three are close to exhausted. Under the headline the window adds “To avoid problems with your computer, quit any applications you are not using.” Some apps in the list may carry the word “(paused)”. That means macOS has stopped them for now so the rest of the Mac keeps responding. Nothing in them is lost yet.
It isn’t a virus warning or a hardware fault. The real message always sits inside the Force Quit Applications window, a separate macOS window that lists your open apps above a Force Quit button. A browser tab that shows a memory warning with a phone number or a download button is a web page pretending, and closing the tab is the whole fix.
Get out of it now
You want the biggest app you can spare, closed with as little lost work as possible.
- If an app still responds, switch to it, save anything open, and quit it with Command-Q. A normal quit lets it save first.
- If nothing responds, select an app in the Force Quit Applications window and click Force Quit. A browser with dozens of tabs is the usual best choice: you lose the open pages, not your documents. Unsaved work in a force-quit app is gone, so leave apps with unsaved documents until last.
- Once memory is free, select any app marked “(paused)” and click Resume.
Restarting the Mac also clears it, but do that only after you’ve saved what you can. Then work out the cause, or the window will be back.
Find the app that used it
Open Activity Monitor (in Applications, then Utilities) and click the Memory tab. Click the Memory column heading so the biggest users are on top; click it again if the smallest are.
Two readings at the bottom matter more than the list. Memory Pressure is a graph, and Apple’s guide reads its colors this way: green, the Mac is using its RAM efficiently; yellow, it might eventually need more; red, it needs more RAM than it has for this work. Swap Used is how much has gone to the disk. Right after the warning, expect the graph in yellow or red and swap measured in gigabytes.
Then read the top of the list. A single app holding far more than everything else is your answer. Browsers spread their memory across many helper processes, often one per tab, so add those up in your head before you judge.
The same check works in Terminal, which is handy when the Mac is struggling:
top -l 1 -o mem -n 10 -stats pid,command,mem
That prints one snapshot: a summary of the whole Mac’s memory, then the ten processes using the most, biggest first.
When the disk is the real problem
Swap lives on the startup disk, so it can only grow while there is free space. On a nearly full disk, macOS can’t add swap files, and the warning can appear even when your apps are behaving normally.
Check the free space:
df -h /
The Avail column is what’s left. Then check how much swap is already in use:
sysctl vm.swapusage
Output looks like this, here from a Mac partway through a heavy day:
vm.swapusage: total = 5120.00M used = 3848.00M free = 1272.00M (encrypted)
If the disk has only a few gigabytes left, freeing space is the real fix, and closing apps only buys time. How much free space a Mac should have covers what macOS needs, and swap files on a Mac explains why the row of swap files grows and shrinks.
An app that keeps growing
If the disk has room and one app tops the list, watch it. Leave Activity Monitor open and note that app’s Memory figure now and again an hour later. Memory that climbs steadily while you do the same work is a leak: the app is asking for memory and never giving it back.
What helps:
- Update the app. Leaks are bugs, and they get fixed.
- Look at its add-ons. Browser extensions, plug-ins and long-running web apps are frequent culprits. Turn them off one at a time.
- Restart it on a schedule. Quitting and reopening a leaky app once a day resets it, which is often enough until a fix ships.
If every app looks modest and the total is simply high, the Mac may be short of memory for the work you give it. How much RAM a Mac actually needs covers that question. Memory on Apple silicon Macs is part of the chip and can’t be added later, so that is a buying decision, not a fix.
Stopping it coming back
- Keep several gigabytes of the startup disk free, so swap always has room.
- Quit apps you’ve finished with instead of leaving them open for days.
- Restart the Mac now and then if it has been up for weeks; it clears whatever has built up.
- Keep an eye on the one app that caused it last time.
Where Foreman fits
Activity Monitor answers the question, but it shows processes, so a browser appears as dozens of rows. Foreman groups each app with its helper processes and adds them up, so the Memory column shows what the whole app is using, and its Performance page graphs memory pressure live. Select the culprit and click End Task: Foreman asks the app to quit the normal way first, so it can offer to save your work, and pressing End Task again within a minute forces it.
Foreman doesn’t free memory by itself and it won’t fix a full disk; it shows you which app to deal with. It’s free for 24 hours, then $12 once.
Questions
Is “Your system has run out of application memory” a virus? No. It’s a standard macOS message, and the real one appears in the Force Quit Applications window, never inside a web page. It means memory and swap are used up, almost always because of one app or a nearly full disk.
What does “(paused)” next to an app mean? macOS has stopped that app for now to keep the Mac responsive. Its windows and data are still there. Free some memory by quitting another app, then select it and click Resume.
Will closing browser tabs help? Yes, often more than anything else. Each tab can hold its own share of memory, and a few heavy web apps left open for days can add up to more than any other app on the Mac.
Should I restart instead of force quitting? Restarting clears memory and swap completely, so it works. It also closes everything, so save first. If the warning returns within a day, the cause is still there, and it is worth finding with the steps above.