Throughout The Witcher 3, any time Yennefer or any of the other sorceresses want to use a portal to teleport to another destination, Geralt will complain and try to take a different route to get to the destination, if possible.
Does Geralt ever specifically mention why he doesn't like to use portals?
Best Answer
He does explain this - in the short story titled "The Last Wish".
In short, it's because sometimes portals misfire, and people indeed come out of them in multiple pieces. Or don't come out at all. Or come out at places completely different from their intended destination.
The relevant quote is as follows:
There is another relevant passage from Season of Storms, the latest published book:
This has since become a running gag, which was popularised most of all by the third game (because there aren't that many portals in the previous games).
All gifs from this Tumblr post, even more gifs in this post.