Einstein's 2nd relativity postulate, does it or doesnt apply to Black holes?

Answer 1

Not at all sure what you mean by Einstein's '2nd relativity postulate.'

Special relativity (1st postulate??) was presented in 1905 and deals mainly with frames of reference, time dilation, etc.,.

General relativity (2nd postulate???) came out in 1907 and that's the one that deals mostly with gravity, acceleration, mass curvature of space-time, etc.,. Solutions to associated general relativity equations implied the existence of black holes.