My Minecraft World Crashes Upon Launch After 1,13 Upgrade

UPDATE THE ISSUE BELOW IS NO LONGER A PROBLEM

So when I made my world I made it in 1.8.9 because that was my favourite version at the time due to the PvP and old traditional blocks. After looking at 1.13 I though mhh I might wanna try that so I upgraded. However after I upgraded straight up to 1.13 my world wouldn't open. When I loaded it it would simply crash and say 'an unexpected error occured. I then tried upgrading my world one version at a time. 1.9, 1.11, 1.12. All these versions worked perfectly fine it's just 1.13 that won't launch. Any solutions? 

THE ABOVE ISSUE IS NO LONGER A PROBLEM

Now when I load it in 1.13 it works! So strange. 

Another issue is. I created the world using the seed 'reindeer' on 1.8.9. The problem is many chunks are glitched or broken. Please see the attached pictures.