Error message because not enough memory (RAM) available

I have a MacBook air and everytime I hit the gradiant button a message pops up that says 'could not complete because not enough memory (RAM) available'. I have gone through and cleared all of my caches and gone to my activity monitor and checked if anything is using a lot of memory and nothing seems out of the ordinary. I have also reset my Illustrator app and nothing so I uninstalled and reinstalled it. still no luck. I have tried updating and restarting my computer and nothing. Thanks in advance!