Error 51900319 in Warlords of Draenor

I’m a member of the Alliance and a Demon Hunter in World of Warcraft. I’ve encountered a recurring error when entering a specific area. I’ve discovered that using the unstuck feature is a workaround, but it’s inconsistent because I can’t rely on it every time. This issue is preventing me from completing certain missions and I don’t know if there is a permanent solution

PS: It’s posted as a Tauren Dark Knight but the bug happens on my Demon Hunter slot