You're working normally, the Mac stalls, and a window appears: your system has run out of application memory, and you should quit apps you aren't using. It comes with a Force Quit list showing apps paused. The confusing part is that it happens on Macs with 16 or 32 GB of memory, and on drives with plenty of space left.

The message isn't really about how much RAM you have. On Golden Gate it's also more likely to show up on certain Macs than it used to be. Here's what triggers it and how to find the cause quickly.

What the warning actually means

Apple silicon Macs share one pool of unified memory between the CPU and GPU. When apps need more than that pool holds, macOS compresses inactive memory and then moves some of it to swap files on your startup drive. That combination normally lets a Mac run far more than its physical memory would suggest, which is why "memory used" in Activity Monitor is often high without any problem.

The warning appears when that system can't keep up. There are two ways that happens.

Cause 1: Not enough free storage for swap

Swap lives on your startup drive. If free space runs low, macOS can't create more swap files, and memory has nowhere to go. Advice from long-time Apple community experts is that low free storage can trigger the warning well before the disk is technically full, especially when apps are requesting a lot of virtual memory.

Cause 2: A process requesting enormous amounts of virtual memory

This is the one that confuses people with plenty of free space. When an app asks macOS for memory address space, the kernel creates page tables to track it, and those page tables live in memory that can't be swapped out. If a process has a memory leak, repeatedly requesting address space and never releasing it, those tables grow until there's no real memory left for anything else. The warning then appears even though your drive has room.

In practice, the second cause is usually one app: a browser with a leaking tab, an Electron app, a container runtime, a virtual machine, or a background agent with a bug.

Fix it right now

When the warning is on screen:

  1. Look at the Force Quit list. Apps using unusual amounts of memory are shown with their usage. The biggest number is your first suspect.
  2. Quit the heaviest app you can afford to lose, saving work first if it responds. Browsers and virtual machines are the usual candidates.
  3. Watch Memory Pressure in Activity Monitor's Memory tab. When the graph returns to green, you're out of immediate trouble. A restart isn't required.

Find the real cause

Once the Mac is responsive, spend five minutes identifying what triggered it, or it will come back.

Sort by memory. In Activity Monitor, click the Memory tab, choose View > All Processes, and sort by the Memory column. Note the top five.

Watch for growth. Check again ten minutes later. A process that keeps growing while you aren't using it is a strong leak candidate.

Get a precise reading from Terminal:

top -o mem -l 1 -n 10 -stats pid,command,mem

Then look closer at a suspect using its process ID:

footprint -p 1234
vmmap --summary 1234 | tail -20

Replace 1234 with the PID. footprint shows how much memory the process really accounts for. vmmap --summary shows how much virtual address space it has reserved. A process with a modest footprint but an enormous virtual size is exactly the pattern behind cause 2.

Check swap and storage:

sysctl vm.swapusage
ls -lh /System/Volumes/VM
df -h /System/Volumes/Data

Large, growing swap files combined with low available space point to cause 1. Plenty of space with the warning anyway points to cause 2.

Common culprits and what to do

Browsers with many tabs. Chromium-based browsers run each tab or extension in its own process. A single misbehaving tab can grow without limit. Use the browser's own task manager to find it, and review extensions.

Electron and web-based apps. Chat, collaboration, and AI desktop apps built on web technology carry their own browser engine. Several running at once can take a large share of memory, and some leak over long sessions. Quitting and reopening them daily is a reasonable workaround until they're fixed.

Container and VM apps. Docker Desktop and virtualization tools reserve memory for their virtual machines. Check their settings and lower the memory allocation to what you actually need.

Apps not yet updated for macOS 27. An app that behaved well on Tahoe can leak on a new OS release. Check for updates, and if one app is consistently responsible, report it to the developer.

A system process. If the top offender is an Apple process, restart, wait for post-upgrade indexing to finish, and if it recurs, report it through Feedback Assistant with a sysdiagnose.

Why 256 GB Macs are more exposed on Golden Gate

This is where cause 1 and the upgrade meet.

On a Mac with a 256 GB drive, Golden Gate's footprint adds up: the new system, Apple Intelligence models that many users see taking well over the 7 GB Apple lists, temporarily inflated System Data after the upgrade, and local Time Machine snapshots. Every gigabyte they take is a gigabyte swap can't use.

We haven't measured this directly, but the logic is straightforward: a Mac that ran comfortably on Tahoe with 30 GB free may hit the warning on Golden Gate with 12 GB free, running exactly the same apps. If you see the warning on a small drive, check free space before anything else.

Keep at least 15–20% of the drive free. On a 256 GB Mac that's roughly 40–50 GB. Our storage guide covers safe ways to get there.

Preventing it

  • Keep free space healthy, especially after major upgrades.
  • Restart occasionally. Long uptimes let slow leaks accumulate.
  • Limit what launches at login in System Settings > General > Login Items & Extensions.
  • Watch Memory Pressure, not Memory Used. Occasional yellow is normal. Frequent red means your workload has outgrown your memory or something is leaking.
  • Report repeat offenders. Leaks get fixed when developers get specific reports.

The short version

  • The warning means memory plus swap can't keep up, not necessarily that your RAM is small.
  • Cause 1: too little free storage for swap. Cause 2: a process reserving huge amounts of virtual memory.
  • Quit the biggest app in the Force Quit list, then find the real culprit with Activity Monitor, footprint, and vmmap.
  • On 256 GB Macs running Golden Gate, check free space first.