Adobe target Error in VEC- Sorry the page requested was refused by server

Hello Folks, 

I am getting errors while creating activities in Adobe Target. Error is "Sorry the page requested was refused by server". I tried with all browsers but still had the same issue. I checked with cookie issue with browser but no issue with it. 

I could see error in console of Adobe target activity page. Is there any issue? It's already worked before. Please advise me.