google_appengine\appcfg.py", line 129, in run_file execfile(_PATHS.script_file(script_name), globals_) NameError: name 'execfile' is not defined

Python 2.7 must be installed for App Engine usage

other workaround when Python 2.7 is not working:

On Windows OS, Go to the "Control Panel" > "Programs & Features" and unistall all the versions of GAE you have.

Go to the path where you had GAE installed, "C:\Program Files (x86)\Google" in your case, and delete the folder "google_appengine" (if you prefer you can do a backup)

Install the lastest version of GAE (1.9.20 actually)

Test to deploy your apps, should work now.