When using a selector with name=, if there is a mob with a custom name or username with a space or symbol in it, the player/mob is not able to be found by the selector.

Test:
1.Summon entity with CustomName with a space/symbol in it.

/summon Pig ~ ~ ~ {CustomName:/,CustomNameVisible:1}

2.Use a selector on entity.

/tp @e[name=/] ~ ~5 ~

3.Errors:
The entity UUID provided is in an invalid format.