Application memory running out!

There are 2 reasons for the "Your system has run out of application memory" dialog box.

A) Your boot disk has very low free storage, and macOS cannot create page/swap files to offload virtual memory contents to disk. This is generally not the case, but I mention because if you do have very low free storage, it might apply. Depending on how much virtual memory is being called for, anything under 50-100GB of free storage may trigger the message. You say you have 120GB free, so this is most likely not your problem.

B) A process (or set of processes) have asked macOS for excessive amounts of virtual memory address space. Virtual memory address space requires macOS to create Virtual Memory Page Tables in the kernel address space to keep track of the application virtual addresses given out. Generally, if there is a memory leak (process asks for a virtual address range, uses the addresses, forgets to give them back, asks for another virtual address range, uses the addresses, forgets again, wash, rinse, repeat), eventually there are so many virtual memory page table entries trying to keep track of the virtual addresses, that macOS no longer has memory available for applications, and you get the "Your system has run out of application memory"

If you look at

Applications -> Utilties -> Activity Monitor -> View (menu) -> All Processes -> Memory (tab)

you can see what processes are using lots of memory. Many of these processes will NOT be applications. Just background agents and daemons used to provide many of the macOS services, as well as 3rd party background processes doing whatever that 3rd party app thinks it should be doing.

Keep in mind that a web browser with lots of open tabs will have a process assigned to each tab, and if you have enough open tabs that adds up. Also not all web sites write good Javascript, and a web page may request more memory they it should causing virtual memory excesses.

Download the Application Etrecheck directly from the Developer.

This is a Diagnostic Tool that makes no changes to the computer.

It makes a coherent and readable inventory of both the Hardware and Software used on the computer 

The application is free or paid from added features. 

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - >>>> using the Additional Text Icon ( 3rd Icon to last ) <<<<

We can have a look at the report for possible issues and may have possible suggestions to resolve the issues

Part 2 of 2

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster and comprising the Operating System

Certain Applications maybe available on the Apple Apps Store - this only means the Developer is prepared to pay Apple a portion on each sale. What the Application may do to the computer is up to the User to check this out before purchase

Any of the below should be removed as per Developers Instructions

This will include CleanMyMac , This will include BitDefender , 

This will included Norton Antivirus , Sophos Av Software

Intego AntiVirus, McAfee, MacKeeper, Avast AntiVirus

Ad Guard, Webroot , ESET , Kaspersky Antivirus. Anti virus

AVG AntiVirus   PowerMyMac 

Trustee  Total AV  avira antivirus   Dr Cleaner Pro Plus

AntiVirus for Mac

F-Secure

Read some of the posting and arrive at your own conclusions.

The The Built in Security  is all that is required.

Hey Shivajyoti,

We see you're having trouble with your Mac running low on memory and we can help.

Application memory means your apps are currently asking for a large amount of RAM access.

You can check the Activity Monitor to review the memory pressure and close any apps that seem to be causing the issue:

In the Activity Monitor app  on your Mac, click Memory (or use the Touch Bar).

The Memory Pressure graph lets you know if your computer is using memory efficiently.

Green memory pressure: Your computer is using all of its RAM efficiently.

Yellow memory pressure: Your computer might eventually need more RAM.

Red memory pressure: Your computer needs more RAM.

If memory pressure is yellow, red, or has spikes, check to see if an app is using up memory and causing the memory pressure to increase. If you no longer need to have the app running, you should quit the app.

Your computer’s memory pressure is accurately measured by examining the amount of free memory available, the swap rate, and the amount of wired and file cached memory to determine if your computer is using RAM efficiently.

Check if your Mac needs more RAM in Activity Monitor

That should help identify the issue.

Thanks for using the Apple Support Communities.