Some bloggers have also reported that they have fixed the WOW51900319 error by resetting the user interface. If the above 3 methods do not work, you can also try this method to get rid of the WOW51900319 error. Here are the easiest steps to fix the problem of resetting the user interface of World of Warcraft.
Close the game completely and check the background.
Uninstalling additional applications from the manager
Go to Battle.net.
Click on the option and select “Show in Finder” in Windows. If you are a Mac OS user, you will see a “Show in Finder” option that you can click on.
Go to the World of Warcraft folder and rename the Cache, Interface, and WTF folders as you see fit.
Relaunches World of Warcraft game application