Minecraft says "Failed to verify username" when I try to go on Multiplayer servers

Yesterday, I changed my Minecraft name from exprandanglous to _Nhite. It shows the change on my profile page on the mojang website, but the change never showed on the Minecraft launcher or in game. This would be fine, except for the fact that I cannot join multiplayer servers due to an error window that pops up saying "Failed to verify username!". How do I fix this?