Minecraft world crashes and shuts down console

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What I expected to happen was...:
My world crashes when opening, it's a creative world about 2 years old I have fixed this by turning off command blocks which are only used for teleportation and world edit and I have no more than 12 

What actually happened was...:
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
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