'Your System Has Run Out of Application Memory' on Mac? Here's the Fix

You’re working in a few Chrome windows, Slack, Spotify, maybe a Photoshop file in the background, and macOS slams the brakes: “Your system has run out of application memory. To avoid problems with your computer, quit any applications you are not using.” Below the dialog is a list of memory hogs you can quit immediately. Your Mac is pleading with you.

This warning is more nuanced than it sounds. It’s not strictly that RAM ran out — modern macOS handles RAM exhaustion via swap. The warning means swap also ran out, or the system is in such heavy thrashing that progress has stalled.

What this warning actually means

macOS uses three memory tiers:

1. Physical RAM — the chips on your logic board. 8, 16, 24, 32 GB or more.
2. Compressed memory — RAM contents the kernel squeezes to make room. macOS does this aggressively.
3. Swap — overflow written to your SSD. Slow but elastic, expanding into free disk space.

The “run out of application memory” warning fires when:

• Active memory plus compressed memory plus swap demand exceeds available swap space.
• A single process is leaking memory faster than the kernel can compress.
• You’re at 99%+ disk usage and macOS literally can’t grow the swap file.

The exact text:

“Your system has run out of application memory. To avoid problems with your computer, quit any applications you are not using.”

Underneath is a list of running apps with Force Quit buttons next to each.

Quick fixes — start here

1. Quit the worst offender immediately

The dialog ranks apps by memory use. The top one is usually the cause. Click Force Quit on it. macOS will free memory and the warning will retreat.

2. Check Activity Monitor for the real picture

Cmd+Space → Activity Monitor → Memory tab. The bottom of the window shows:

• Memory Used — physical RAM in use.
• Cached Files — RAM the OS will release on demand. Don’t worry about this number.
• Swap Used — overflow on disk. If this exceeds 5 GB consistently, your Mac is undersized for your workload.
• Memory Pressure graph — the only number that matters for the warning. Green = fine. Yellow = under pressure. Red = the dialog is imminent or here.

Sort the Memory column descending. The top entry often surprises people: Chrome with 40 tabs open routinely uses 8+ GB; a leaking Electron app can hit 12 GB.

3. Restart the Mac

If you can quit nothing else, restart. All swap clears, all leaked memory frees. This buys you time to identify the leaker for next time.

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Find the actual memory hog

Activity Monitor’s Memory column tells you current usage, but a brief leak might not show. Better diagnostic:

1. Activity Monitor → View → All Processes.
2. Sort by Real Memory (the actual RAM the process is using, not virtual address space).
3. Look for processes you don’t recognize. Some examples:
   • WindowServer — the macOS GUI. Normal range: 200 MB to 1 GB. If it’s 5 GB, there’s a graphics-related leak; restart fixes it.
   • kernel_task — kernel itself. Normal range: 1–2 GB. If it’s higher, a kext or driver is misbehaving.
   • mds and mds_stores — Spotlight indexing. Can spike during heavy file changes; normal at 1 GB.
   • com.apple.WebKit.Networking — Safari tabs. Each tab is a separate process now.

Click the small “i” button on a suspicious process to see detailed memory breakdown. The “Open Files and Ports” tab tells you what the process is doing.

Browsers: the usual culprit

Browser processes routinely cause memory warnings. Specifically:

• Chrome with 30+ tabs can exceed 10 GB on its own.
• YouTube tabs left open for hours leak memory in some Chrome versions.
• Slack in a browser tab holds about 800 MB even idle.
• Figma documents can use 4+ GB of GPU and system memory each.
• Google Meet or Zoom in browser doubles memory use during calls.

Specific moves that help:

1. Close tabs you haven’t visited in an hour. Use The Great Suspender alternatives or Chrome’s built-in tab grouping with auto-suspend.
2. Use Safari for tabs you keep open all day. It’s noticeably leaner than Chrome.
3. Quit Slack/Discord/Teams when not on call.
4. Restart your browser daily — leaks accumulate over the day.

Make swap actually work

The warning often means swap is constrained. To see how much swap is allocated:

sysctl vm.swapusage

If total = 0 while you’re under pressure, your startup disk is too full to grow swap. Free disk space and the warning frequency drops dramatically.

A Mac with under 5 GB free disk space will hit this warning constantly because swap can’t expand. Get back to at least 20 GB free.

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When a single app is leaking

If the same app appears at the top of memory use repeatedly, even after restart, suspect a memory leak in that app.

To confirm:

1. Quit the app.
2. Note baseline memory use.
3. Open the app and use it as you normally would.
4. After 30 minutes, compare memory growth.
5. Apps that grow steadily without releasing are leaking.

Common leakers historically:

• Electron apps in general (Slack, Discord, Notion, VS Code, Figma desktop).
• Certain Safari extensions, especially older ad blockers.
• Adobe Creative Cloud helper processes.
• Some macOS Mail accounts (especially Exchange) under heavy attachment use.

Update the app first — leaks get fixed regularly. If updating doesn’t help, restart the app daily as a workaround while you wait for the developer.

Activity Monitor’s “Memory Compressed” number

Compressed memory is RAM the kernel has squeezed in place. It’s still RAM, but it’s now half the size. If you see 4 GB compressed on a 16 GB Mac, that’s 4 GB of work happening in 2 GB of physical chips. This is normal; macOS is doing its job.

The warning sign is when Memory Pressure goes red while Compressed Memory is high — the kernel can’t compress fast enough to keep up.

Specific scenarios

Memory warning during sleep wake

The Mac wakes from sleep and immediately shows the warning. Usually because a background process re-loaded its full state on wake. Check Activity Monitor for processes with high CPU TIME (cumulative CPU since launch). High cumulative time on a process you wouldn’t expect means it’s been running hot in background.

Memory warning while idle

You walked away, came back, the warning was there. Likely a runaway process. Common offenders: cloud sync clients (iCloud, Dropbox, Google Drive) processing a large change set; Spotlight reindexing after a software update.

Memory warning while on video calls

Zoom and Teams both spike to 2+ GB during calls; combined with Chrome they push past available memory on 8 GB Macs. Quit other apps before joining calls.

Permanent fixes if it keeps happening

1. Reduce login items

System Settings → General → Login Items. Disable apps that auto-launch but you don’t always need.

2. Disable Spotlight on irrelevant volumes

System Settings → Siri & Spotlight → Spotlight Privacy → add external drives or volumes you don’t search. Each indexed volume consumes RAM.

3. Replace heavy apps with lighter alternatives

• Slack → Slack in Safari (less memory than the desktop app).
• VS Code → Sublime Text or Nova for non-extension work.
• Notion → Bear or Obsidian for notes.
• Photoshop → Pixelmator Pro for most edits.

4. Add RAM (Intel Macs only)

If you have a 2018 or earlier Intel Mac with user-replaceable RAM, an upgrade is the surest fix. Apple Silicon RAM is unified with the SoC and not upgradeable.

5. Buy a Mac with more RAM

If you’re consistently exceeding your 8 GB Mac’s capacity, a 16 GB or 24 GB Mac will end the problem. The base RAM allocation has been the bottleneck for years.

When to call Apple

If memory warnings persist on a 16 GB or larger Mac with no obvious leaker, suspect hardware. Run Apple Diagnostics (Apple Silicon: power on, hold power, choose Options, then Cmd+D from there; Intel: hold D at boot). PFM error codes mean failing memory. That’s an Apple Support call.

The memory warning is mostly a symptom of either too little RAM for your workload, a leaking app, or a too-full disk strangling swap. Three problems, three different fixes. Knowing which one applies makes the difference between a five-minute fix and a Tuesday spent hunting ghosts.