This is an error you run into when the JVM Heap tells you “Enough is enough. I can’t fit all of this into my memory.” Which usually means that the application has become unstable and should be restarted before it crashes and that you also have a real problem to solve.
The following things can cause this error:
Introduced by developer, custom code
A bug in Mendix Runtime
A bug in a Java library used by custom code of the developer or by the Mendix Runtime
A bug in Java Runtime
Massive creation of objects (for example, by retrieving 1 trillion entities in a single microflow at once)
Configuration issue or sizing issue.
You can refer to this doc.
you can correct this by
Settings→ config.→ Size
Do one more thing
There maybe the case that a microflow of yours is going in infinite loop. So, to check that,
kindly go to console, there's an advance option, now go to log now search for microflow and set it to trace, this will tell you which activity of yours is going in an infinite loop.