A few times recently my MacMini running 10.14.6 gets into a loop of giving this error every few minutes to seconds. This is despite having 1.5-3GB application memory free, according to the Memory Clean 3 app. Even using it to clean the memory doesn't help. Eventually it just grinds to a halt and rebooting is the only answer.
Anyone else seen this, or can suggest a remedy short of rebooting?