Once a nether portal is created and a player enters and subsequently leaves the nether, if you dismantle the portal in the overworld and make another portal somewhat near the original portals location, the player can then enter the nether through the portal at the new location. However, when that player leaves the nether, a new nether portal will be generated in the overworld at a location near where the first portal was located. I did not have any crashes prior to this issue, and having tested this several times it works every single time but will then cause a crash moments after returning to the overworld.