src/Tools/VSCode/extension/package.json

         "mocha": "3.x",
         "@types/node": "^6.0.40",
         "@types/mocha": "^2.2.32"
     },
     "dependencies": {
-        "vscode-languageclient": "^2.6.3"
+        "vscode-languageclient": "3.0.x"
     }
 }