kernelapp is in ipython_kernel

not jupyter_client

ipython_kernel/connect.py

@@ -151,7 +151,7 def get_connection_file(app=None):
         If unspecified, the currently running app will be used
     """
     if app is None:
-        from jupyter_client.kernelapp import IPKernelApp
+        from ipython_kernel.kernelapp import IPKernelApp
         if not IPKernelApp.initialized():
             raise RuntimeError("app not specified, and not in a running Kernel")
 

jupyter_client/connect.py

@@ -151,7 +151,7 def get_connection_file(app=None):
         If unspecified, the currently running app will be used
     """
     if app is None:
-        from jupyter_client.kernelapp import IPKernelApp
+        from ipython_kernel.kernelapp import IPKernelApp
         if not IPKernelApp.initialized():
             raise RuntimeError("app not specified, and not in a running Kernel")