Game crash, Infinite loading, cannot save

Minecraft is able to start up but more than half the time, it will not load once you click play. It will have the loading screen icon constantly going and never stop. In addition, resuming (or starting a new world) a world may have it stuck at Loading Spawn Point indefinitely. Even if you get past that, whenever a save happens, it will crash saying Minecraft has failed to load.

It is completely unplayable at the moment.

This has not occurred at all for version 1.37 and it was until update 1.39 when the problem started happening. (No idea for 1.38 since I missed the update)

No mods or skins used. Tried turning autosave on and off which didn't affect anything.