Protection stack overflow on starting R session

Recently I have started getting this error as soon as I reload R session - right at the beginning.
Error: protect(): protection stack overflow

To give you some clues I have started using Keras for R package for deep learning.
I use an iMac with 8 GB of RAM and there doesn't seem to be a memory strain as I see from the activity log of my machine.

Any chance you would be able to provide a reproducible example? E.g. a standalone Keras script that when executed causes the associated protection issue when attempting to restart the R session?

Difficult but am trying to do.

I am seeing this as well. I have a 65MB .RData file that seems to be causing it (when rename the file before startup the message goes away). Unfortunately that file contains data that I'm using for research. Is there something I could do on my end to try & isolate the problem to avoid sharing the data?

Do you see the same error if you launch R from outside of RStudio (e.g. using RGui or R from the terminal)?

Is there anything unique about your R workspace; e.g. does it contain a very large number of objects?