java.lang.NullPointerException: How do I fix this error?

Whenever I try to open a multiplayer server or lan, it gives me that error and I have no idea how to fix it correctly. No matter what I do, nothing helps.

In case you're wondering, my laptop has a Nvidia Geforce 940m GPU, and an Intel Duel-Core i5, with 8 gigabytes of RAM. My display is 1920x1080p.