Errors

“Your system has run out of application memory” on a Mac

By the Noah team·Updated September 15, 2026·5 min read

Short answerThis panel comes from macOS itself, not from the app on top. It means macOS could not give a program the memory it asked for — not that your memory is full, which is why it appears on Macs with gigabytes free. Force quit the largest app listed to get control back, save your work, then check three things:

One app's memory kept growing — a single program climbing until macOS ran out of room. Quitting it ends the message.
The boot disk is nearly full — macOS keeps overflow memory in a file on the drive, and a full drive leaves nowhere to put it. Free space fixes it.
The work genuinely doesn't fit — heavy apps on a small-memory Mac. Fewer things open, or more memory.

Don't install a memory cleaner. Nothing on this page needs one.

A window titled Force Quit Applications is covering your screen. It reads “Your system has run out of application memory.” Below it, a list of your open apps and a Force Quit button. Nothing responds properly until you deal with it.

The message misleads almost everyone who sees it, because it appears on Macs with plenty of memory free. It is not a report that your memory is full. It is macOS saying it could not hand a program the memory that program asked for — and there are three quite different reasons for that.

What the message actually means

The panel is drawn by macOS, not by whichever app was in front. On a Mac running macOS 26 the wording lives in a system file belonging to loginwindow, the part of macOS that manages your logged-in session. So the message is not evidence that one app is broken, and it is not a virus.

Your Mac keeps running programs in its fast working memory — RAM. When RAM fills, macOS moves the least-used parts to a file on the drive and reads them back when needed. That file is called swap. The message appears when macOS cannot satisfy a request for more memory from either place.

That is why the number in Activity Monitor can look healthy while this panel is on screen. Apple's own guidance points the same way: “When you have free or unused memory, your computer performance does not necessarily improve. macOS obtains the best performance by efficiently using and managing all of your computer's memory.”

First, get control back

Before diagnosing anything, clear the panel. Pick the app highest in its list that you can afford to lose, and click Force Quit.

Fixforce quitting ends an app immediately and does not save your work. Choose the one holding least, and the moment the panel clears, save everything else that is open.

If your Mac is too unresponsive to click anything, hold the power button until it switches off, then start it again. You lose unsaved work either way, and a restart empties swap, so the Mac comes back with room.

One app's memory kept growing

The message arrives after hours or days with the same app open. It often names one program you left running — a browser with many tabs, a mail client, a design tool.

A program can keep asking for memory and never give it back. Each running program is a process — one live copy of an application. When one process climbs without limit, it takes the room every other program needs, and macOS eventually refuses the next request.

Sort your programs by size and the offender usually stands out. Open Activity Monitor (⌘ Space, type Activity Monitor), pick the Memory tab, and click the Memory column heading. Terminal can rank them as well, using a different measure:

zsh — Terminal

% ps -axo pid,rss,comm | sort -k2 -n | tail -5

Sample result

75169 786896 /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
44342 869824 code-cli
69483 886816 /Applications/Google Chrome.app/…/Google Chrome Helper (Renderer)
93311 910752 /System/Library/Frameworks/Virtualization.framework/…/VirtualMachine
35944 940160 editor

One real reading, with paths shortened and two program names replaced by same-length placeholders; every number and the row order are exactly as measured. The middle column is resident memory in kilobytes (man ps), so divide by 1024 for megabytes — 910752 is about 889 MB. Resident memory and the physical footprint macOS reports for the same program diverge in both directions. Measured at that moment: Google Chrome showed 768 MB resident against a 462 MB footprint, while the VirtualMachine row showed 889 MB resident against 1.8 GB. So read this column as a ranking, not as an exact size. One browser also spreads across many rows — Chrome had 23 separate renderer entries here — so add them up before blaming one line.

Fixquit the largest one you can spare, saving first. If the message stops coming back, that program was the cause — update it, or report the behaviour to whoever makes it.

NoahNoah reads this same list and names the largest programs with their sizes, alongside total memory, swap in use, and how full the boot disk is. The list includes parts of macOS, which should be left running. With your approval it can quit the process you pick, so save your work first. It does not read the Memory Pressure graph. It cannot tell that this message appeared, so say that you saw it.

The boot disk has no room left

Activity Monitor shows memory to spare, the message appears anyway, and the Mac has been low on storage for a while.

Swap lives on the drive. When the drive is nearly full, macOS has nowhere to put the overflow, so a request for memory fails even though the memory chips are not the limit. This is the cause that explains a message on a Mac with gigabytes free.

Check the volume that holds your files. On modern macOS the startup volume is split in two, and the half mounted at / is sealed and read-only — checking it reports almost no usage and tells you nothing.

zsh — Terminal

% df -h /System/Volumes/Data

Check this volume, not /, which holds the sealed copy of macOS. Or open Apple menu > System Settings > General > Storage.

Fixfree space on that volume — empty the Trash, remove large files you have copies of, and move archives to an external drive. Space returned to the drive is space macOS can use for swap again.

The work genuinely doesn't fit

The message returns within hours of every restart, no single program dominates the list, and everything open is something you actually use.

Sometimes nothing is broken. A large photo library, several design apps, a virtual machine and a browser full of tabs can simply be bigger than the memory installed. Swap covers a gap; it cannot cover a permanent shortfall, and the drive is far slower than RAM.

Apple's Memory Pressure graph is the honest read here. Open Activity Monitor's Memory tab and read its colour. Apple describes green as “Your computer is using all of its RAM efficiently”. Yellow means “Your computer might eventually need more RAM”, and red means “Your computer needs more RAM.”

Fixkeep fewer things open at once, and quit apps fully with ⌘ Q rather than closing their windows. If the graph lives in the red during ordinary work, more memory is the only real answer, and memory is not upgradeable on current Macs.

What not to do

Memory cleaners sell this message hard. Skip them. They work by forcing macOS to drop memory it was deliberately holding for reuse, which makes the next few minutes slower and fixes none of the three causes above.

Fixignore the “free memory” number entirely. Watch the Memory Pressure graph and your free storage instead. Those two move for real reasons.

The short version

Force quit the largest app you can afford to lose, then save everything.
Activity Monitor > Memory, sorted by size: one program far above the rest is your cause.
Check storage on /System/Volumes/Data, not / — a full drive causes this on a Mac with free memory.
Message back within hours of a restart, with nothing dominating? The workload is bigger than the memory.
No cleaner app is part of any of these fixes.

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Frequently asked questions

What does “Your system has run out of application memory” mean on a Mac?

It means macOS could not give a program the memory it requested. It does not mean your RAM is full, which is why the message appears on Macs with gigabytes free. Three things cause it: one program whose memory kept growing, a boot disk too full for macOS to store overflow memory on, or a workload genuinely larger than the memory installed. The panel itself comes from macOS, not from the app in front.

Why do I get this message when I have plenty of RAM free?

Most often because the startup drive is nearly full. macOS keeps overflow memory in a file on the drive, so when the drive has no room, a request for memory can fail while the memory chips still have space. Check storage on the data volume — df -h /System/Volumes/Data in Terminal, or System Settings > General > Storage. Checking / instead is misleading, because that volume is sealed and read-only and always reports low usage.

Is this error a virus?

No. The wording is built into macOS itself. It lives in a system file belonging to loginwindow, the part of macOS that runs your logged-in session. macOS shows the panel when it cannot satisfy a request for memory. It is a resource message, not a sign of infection, and no security tool is needed to clear it.

How do I stop it from happening again?

Work out which of the three causes applies. If one program sits far above everything else in Activity Monitor's Memory tab, quit it and keep it updated. If your startup drive is nearly full, free space on it. If the message returns within hours of every restart, with no single program dominating, the workload is larger than your memory. The fix is running fewer apps at once, or moving to a Mac with more memory.

Do memory cleaner apps fix this?

No. They force macOS to release memory it was holding for reuse, which slows the next few minutes and addresses none of the three real causes. Apple's own guidance is that free memory is not the goal. Apple writes: “When you have free or unused memory, your computer performance does not necessarily improve.” Watch the Memory Pressure graph and your free storage instead.

Will restarting fix it?

Restarting clears the message and empties swap, so the Mac comes back with room — but it only buys time if something is still wrong. If the message returns after a few hours or days, use that interval as the clue. Days points at one program's memory slowly growing. Hours points at a full drive, or at a workload bigger than the memory installed.

Commands in this guide are standard, read-only macOS diagnostics unless noted; anything that changes your system is called out. When in doubt, back up first with Time Machine.