Terraria Error (Loading)

[Ghostly!]

Im not sure were the error came from but i would like some help to fix this error ,when i attempt to load the game the game doesn't display with its window or anything instead but states that the the app is already running instead a small window appears saying.(Typed in the Exact wording)

System.NullReferenceExecption: Object reference not set to an instance of an
object.
at Terraria.IO.Preferences.Put(String name, Object value)
at Terraria.Main.SaveSettings()
at Terraria.Main.OpenSettings()
at Terraria.Main.Initialize()
at Microsoft.Xna.Framework.Game.RunGame(Boolean use BlockingRun)
at Terraria.Program.InternalMain(String[] args)

I've tried these so far
-Uninstalling and reinstalling
- Use task manager cancel steam and terraria backround program

that is as far is it goes i hope this is fixiable and easy i would deeply apreccitate any advice and suppot to solve it.
Thank You

 

[Ghostly!]

I'm having a similar problem...

There is a part wrote in portuguese, translated it says:
...Exception: It has already been added an item with the same key.
in System.Throw...
in System.Collections...
in Terraria.Utils...
in Terraria.Program...

when you started terraria did it tell you the app was already running or you just only got this?

 

[JK0]

when you started terraria did it tell you the app was already running or you just only got this?

I just got this message :s
But I'm opening Terraria from Steam folder and it's not happening that, I think it's an integration problem between Terraria and Steam.

 

[ski_bow17]

i got the first message as well but it doesn't go away and there are no new updates so i'm lost