Traceback (most recent call last):


 "/home/pi/scratch/ranger/ranger/core/main.py", line 171, in main

fm.initialize()


 "/home/pi/scratch/ranger/ranger/core/fm.py", line 132, in initialize

self.ui.initialize()


 "/home/pi/scratch/ranger/ranger/gui/ui.py", line 127, in initialize

self.handle_multiplexer()


 "/home/pi/scratch/ranger/ranger/gui/ui.py", line 500, in handle_multiplexer

['screen', '-Q', 'title']).strip()


 "/home/pi/scratch/ranger/ranger/ext/spawn.py", line 35, in check_output

process = Popen(popenargs, stderr=fd_devnull, **kwargs)


 "/usr/lib/python3.7/subprocess.py", line 775, in __init__

restore_signals, start_new_session)


 "/usr/lib/python3.7/subprocess.py", line 1522, in _execute_child

raise child_exception_type(errno_num, err_msg, err_filename)

NotFoundError: [Errno 2] No such file or directory: 'screen': 'screen'

Traceback (most recent call last):

 "/home/jsha/certbot/venv/bin/certbot", line 9, in <module>
load_entry_point('certbot', 'console_scripts', 'certbot')()

 "/home/jsha/certbot/certbot/main.py", line 770, in main
return config.func(config, plugins)

 "/home/jsha/certbot/certbot/main.py", line 565, in obtain_cert
_, action = _auth_from_domains(le_client, config, domains, lineage)

 "/home/jsha/certbot/certbot/main.py", line 104, in _auth_from_domains
lineage = le_client.obtain_and_enroll_certificate(domains)

 "/home/jsha/certbot/certbot/client.py", line 275, in obtain_and_enroll_certificate
certr, chain, key, _ = self.obtain_certificate(domains)

 "/home/jsha/certbot/certbot/client.py", line 247, in obtain_certificate
self.config.allow_subset_of_names)

 "/home/jsha/certbot/certbot/auth_handler.py", line 70, in get_authorizations
resp = self._solve_challenges()

 "/home/jsha/certbot/certbot/auth_handler.py", line 114, in _solve_challenges
assert len(resp) == len(self.achalls)TypeError: object of type 'NoneType' has no len()