running a late 21013 27-inch imac with high sierra 10.13.6 os. when i solved my safari problem 2 days ago, i was so frustrated, i began the process of setting up all new bookmarks on firefox. what a pain.
then i saw this thread in my email. i almost didn't read it. after several unsuccessful attempts with different startup procedures using different combinations of keys, etc., i read 7 of the 8 pages of responses in their entirety before i found one that i had enough time to try: reinstall the safari update. it worked. so simple, but i never thought of it because the update was almost brand new. since there were no further upgrades indicated under "software update," i assumed (perhaps incorrectly) i had the most recent version.
problem solved. until someone proves me wrong, i have to think apple simply didn't respond to this thread, or even to its own geniuses, who, in my experience, seem to know almost everything. all's well now with my safari 13.1 (13609.1.20.111.8). apple9055 - that looks like the same version you're trying to run without success, so perhaps it was patched without changing the version number? don't know... just happy it worked. hope it works for all of you!