I'm currently having the same issue, any i can't play more than 1 hour and it will crash with:

An unexpected error has occurred. Exiting FINAL FANTASY XIV.
2019-08-20_12:42

ffxiv_dx11.exe+43974E
ffxiv_dx11.exe+F5D47A
ffxiv_dx11.exe+F5F97D
ffxiv_dx11.exe+17D5A0
ffxiv_dx11.exe+17BE18
ffxiv_dx11.exe+1A07E2
ffxiv_dx11.exe+11F0189
KERNEL32.DLL+17BD4

I got this error today when trying to play. I tried doing some changes that i found on the forums like creating custom profiles on my gpu for the game, putting my monitor from 144 to 60Hz and play at lower resolution.
But until now i got no luck.