First, I forgot to mention, this error came up when I was in JRebel debug mode.
For now, none of the existing solution worked. But I did the following:
1. I upgraded to later version of intellij (2019.3). everything stop running and all sort of error came up.
2. I reverted back to the version I was using (2019.2)
3. then I did rebuild with default debug mode icon (little red bug icon) then with jrebel debug mode icon (rocket with a grey bug). Only Jrebel debug mode have that error message!
I still did not know why jRebel acts like that suddenly, but at least this is a piece of information that may help lead to better solution than what I would have to do now ---- use default Intellij debug mode.... which is very very slow....
So likely you may not even need to take any of the above step, but simply try to build with the Intellij Debug mode to see if it still work so to isolate out that if its a JRebel problem.