Hello, Maneubert!
When you load the game, there must not be any third-party applications that may influence the game process installed neither in your browser nor on your PC.
Please use only browsers and official applications Facebook Gameroom, Plarium Games app downloaded from official sources to play the game.
If you don’t use any third-party software or you are not sure if there is one installed in your browser, please try to clear the cache of your browser or official application, also restart the game, close the alert window and wait until the game is loaded.
As using third-party applications to play Vikings: War of Clans refers to the violation of the Terms of Use, the access to the game for players using such software will be restricted.