Let's encrypt doesn't renew

Hi

When I try to renew my certificate I get the following error:

On an earlier version of certbot (0.35) it worked

Please paste the error text into your post. You can put three backticks before and after it to preserve formatting.
image

like this
2020-01-27 15:24:23,193:DEBUG:certbot.main:certbot version: 0.39.0
2020-01-27 15:24:23,194:DEBUG:certbot.main:Arguments: ['--webroot', '--webroot-path', '/var/www/html/', '--text', '--non-interactive', '--agree-tos', '--email', '------@---.----.pl', '-d', '-----.------.----.pl', '--test-cert', '--quiet']
2020-01-27 15:24:23,194:DEBUG:certbot.main:Discovered plugins: PluginsRegistry(PluginEntryPoint#manual,PluginEntryPoint#null,PluginEntryPoint#standalone,PluginEntryPoint#webroot)
2020-01-27 15:24:23,247:DEBUG:certbot.log:Root logging level set at 30
2020-01-27 15:24:23,247:INFO:certbot.log:Saving debug log to /var/log/letsencrypt/letsencrypt.log
2020-01-27 15:24:23,248:DEBUG:certbot.plugins.selection:Requested authenticator webroot and installer None
2020-01-27 15:24:23,250:DEBUG:certbot.plugins.selection:Single candidate plugin: * webroot
Description: Place files in webroot directory
Interfaces: IAuthenticator, IPlugin
Entry point: webroot = certbot.plugins.webroot:Authenticator
Initialized: <certbot.plugins.webroot.Authenticator object at 0x7f2af0baef90>
Prep: True
2020-01-27 15:24:23,250:DEBUG:certbot.plugins.selection:Selected authenticator <certbot.plugins.webroot.Authenticator object at 0x7f2af0baef90> and installer None
2020-01-27 15:24:23,250:INFO:certbot.plugins.selection:Plugins selected: Authenticator webroot, Installer None
2020-01-27 15:24:23,946:DEBUG:acme.client:Sending GET request to https://acme-staging-v02.api.letsencrypt.org/directory.
2020-01-27 15:24:23,954:INFO:requests.packages.urllib3.connectionpool:Starting new HTTPS connection (1): acme-staging-v02.api.letsencrypt.org
2020-01-27 15:24:43,979:DEBUG:certbot.log:Exiting abnormally:
Traceback (most recent call last):
  File "/usr/bin/certbot", line 9, in <module>
    load_entry_point('certbot==0.39.0', 'console_scripts', 'certbot')()
  File "/usr/lib/python2.7/site-packages/certbot/main.py", line 1378, in main
    return config.func(config, plugins)
  File "/usr/lib/python2.7/site-packages/certbot/main.py", line 1249, in certonly
    le_client = _init_le_client(config, auth, installer)
  File "/usr/lib/python2.7/site-packages/certbot/main.py", line 607, in _init_le_client
    acc, acme = _determine_account(config)
  File "/usr/lib/python2.7/site-packages/certbot/main.py", line 523, in _determine_account
    config, account_storage, tos_cb=_tos_cb)
  File "/usr/lib/python2.7/site-packages/certbot/client.py", line 176, in register
    acme = acme_from_config_key(config, key)
  File "/usr/lib/python2.7/site-packages/certbot/client.py", line 46, in acme_from_config_key
    return acme_client.BackwardsCompatibleClientV2(net, key, config.server)
  File "/usr/lib/python2.7/site-packages/acme/client.py", line 828, in __init__
    directory = messages.Directory.from_json(net.get(server).json())
  File "/usr/lib/python2.7/site-packages/acme/client.py", line 1161, in get
    self._send_request('GET', url, **kwargs), content_type=content_type)
  File "/usr/lib/python2.7/site-packages/acme/client.py", line 1110, in _send_request
    response = self.session.request(method, url, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 464, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/lib/python2.7/site-packages/requests/sessions.py", line 576, in send
    r = adapter.send(request, **kwargs)
  File "/usr/lib/python2.7/site-packages/requests/adapters.py", line 415, in send
    raise ConnectionError(err, request=request)
ConnectionError: ('Connection aborted.', gaierror(-2, 'Name or service not known'))
2020-01-27 15:24:43,982:ERROR:certbot.log:An unexpected error occurred:

What version of certbot are you using? certbot --version should tell you; if that errors out, rpm -q certbot should work.

certbot-0.39.0-1.el7.

Trying to update the server from version 7.6 to 7.7 … unfortunately an error pops up

Maybe you already did it but…
Take a read

Backup your server before continue
yum install nethserver-subscription
then try to update from 7.6 to 7.7