When you are using WoW Server of a particular region then it might be overloaded. The number of pins could be could be one of the reasons for it to be overloaded. This will, in turn, causes wow51900319 which need to be fixed immediately. This is because the wow server will be disabled thereby not allowing it to serve any requests. In such cases, it is highly recommended to make use of VPN of some other region except the one you are using. For this method to change your location which will ensure that the server is different. By doing so the error will be fixed immediately.