Your System Has Run Out of Application Memory on Mac: What to Do First
The “Your system has run out of application memory” window tends to appear when you are in the middle of something you cannot easily repeat. Save open documents first. Then quit an app you do not need right now, starting with a large browser session, virtual machine, or creative project. Use Force Quit only for an app that will not respond, because unsaved changes in it can be lost.
This warning concerns the memory available to running apps. It is not the same as a “startup disk almost full” warning, although macOS also uses space on the startup disk for swap. Deleting a few downloads does not make a runaway app release memory.
Get the Mac responsive without losing more work
- Save in every app that still responds. If a long export or transfer is finishing, let it finish before closing its app when possible.
- Use the warning to identify an app whose work is already saved and that you do not need right now. If it responds, switch to the app and choose Quit from its menu. The warning window's Force Quit button is not a normal quit.
- If an app is frozen, use Apple menu › Force Quit, select that app, then force quit it. Apple warns that a normal quit gives the app a chance to save changes, while a forced quit may not.
- Once the Mac responds, open Activity Monitor › Memory. Note the Memory Pressure graph and the largest processes before restarting, so the likely cause is still visible.
Do not force quit an unfamiliar system process because its Memory number is high. Identify the app or process first; a browser can spread its tabs and extensions across several helper rows. If you cannot save or quit anything and the Mac remains unresponsive, a restart may be necessary, but unsaved work is at risk.
Find out why the warning appeared
The Activity Monitor memory guide defines App Memory as memory used by apps, Compressed as memory compressed to make room, and Swap Used as startup-disk space used to move pages in and out of RAM. The Memory Pressure graph combines several signals; a large Memory Used figure alone does not diagnose this warning.
| What you see after recovering | What to check next |
|---|---|
| One app keeps growing as you repeat the same action | Save, quit and reopen it, update it, then report reproducible growth to its developer |
| Pressure returns to green after a large app quits | Reduce that app's active tabs, project size, or assigned virtual-machine memory if its work allows |
| Several required apps together keep pressure yellow or red | Run fewer demanding jobs at once; the normal workload may need more physical memory |
| Pressure is green but the Mac is still slow | Look at CPU, thermals, and disk activity instead of clearing RAM |
If the startup disk also has very little free space, check System Settings › General › Storage. Apple explains that Storage reports disk capacity and that files moved to the Trash still occupy space until it is emptied. Freeing disk capacity can leave room for files and swap, but it does not by itself cure an app that keeps allocating memory. Review files before deleting them; do not remove swap files or random system folders by hand.
For a closer reading of the graph, see Mac Memory Pressure explained. Swap Memory explained covers why a non-zero Swap Used value alone is normal. This article is for the moment the warning interrupts work, not for making the free-RAM number look larger.
If it happens again
Record which apps were open, the largest few Memory rows, Memory Pressure, Swap Used, and what you were doing immediately before the warning. After a normal restart, repeat the same task. If one app grows on each attempt, its tabs, plug-ins, document, or an app bug are better leads than a general cleaner. If only a full set of necessary apps triggers sustained pressure, reducing concurrent work or choosing more memory on a future Mac addresses the actual limit. Apple notes that available RAM should be judged by Memory Pressure, not the free-memory count.
FAQ
Should I force quit the app using the most memory?
Save its work and try a normal quit first. Force quit only if it does not respond or the warning leaves no workable alternative; open files may lose data.
Will deleting files fix the application-memory warning?
Only low disk space is a reason to free disk capacity. The warning is about app memory demand; deleting downloads cannot stop an app from allocating RAM. Check the Memory tab and, separately, Storage when the startup disk is nearly full.
Should I use a RAM cleaner or disable swap?
No. macOS already reclaims cached memory when apps need it. A cleaner does not fix the app or workload causing the warning, and swap is part of how macOS handles memory demand. See whether you need a Mac memory cleaner.