Hello, I was having the backend error bug since I installed the game on my computer and I found a work around to it.
What I did was:
1)Download and installed steam.
2)Click on the Library tag
3)Cliked on "ADD A GAME"
4)There I selected were my game was installed in this case the root was C:\Games
5)I launched the game from there and had not problem login in.
I want to add that, after doing this the error completely dissapeared even if I start the game using the launcher and not steam.
If you have any question please ask.