Kaushal - can you explain what is the difference and why “make" doesn’t work but "make bootstrap" does?
# make bootstrap
# Removes all the compiled files to force a new bootstrap from a
# clean slate, and then build in the normal way.
So bootstrap ensures that you don't try to use old compiled files which might be incompatible with the new source files. I am not a core dev, just a user. But I have noticed that that tends to happen once every few months on so on the master branch.