Sudo snap install core ошибка

I have the hello snap, notes and core installed on my computer and all of them work fine.

$ snap list
Name              Version           Rev  Developer         Notes
core              16.04.1           714  canonical         -
hello             2.10              20   canonical         -
notes             0.9.0~gitb6e3b34  4    notes-developers  -  

When the hello snap is installed, the core snap is installed along with it if core is not already installed. Try updating the core snap:

sudo snap refresh core  

If core is already installed the following message will be shown:

snap "core" has no updates available

Your results of running sudo snap refresh core were as follows:

sudo snap refresh core error: cannot refresh "core": cannot find snap "core"

So uninstall the core snap and then reinstall it.

sudo snap remove core hello  
sudo snap install hello # core will also be installed automatically

Hello is a terminal app that runs like this.

$ hello
Hello, world!

I am trying to get and install some https certificates for apache on Debian 10 by following this: https://certbot.eff.org/lets-encrypt/debianbuster-apache

Everything is going fine until step 7: sudo certbot --apache:

An error occurred while fetching Certbot snap plugins: your version of snapd is outdated.
Please run "sudo snap install core; sudo snap refresh core" in your terminal and try again.
An unexpected error occurred:
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: http://snapd/v2/connections?snap=certbot&interface=content
Please see the logfile '/tmp/tmp5xjbr23v/log' for more details.

When I run sudo snap install core; sudo snap refresh core:

snap "core" is already installed, see 'snap help refresh'
error: cannot refresh "core": refreshing disabled snap "core" not supported

Looking at the log (/tmp/tmp5xjbr23v/log):

2020-11-04 00:26:04,950:DEBUG:urllib3.connectionpool:http://localhost:None "GET /v2/connections?snap=certbot&interface=content HTTP/1.1" 404 88
2020-11-04 00:26:04,951:ERROR:certbot._internal.snap_config:An error occurred while fetching Certbot snap plugins: your version of snapd is outdated.
2020-11-04 00:26:04,951:ERROR:certbot._internal.snap_config:Please run "sudo snap install core; sudo snap refresh core" in your terminal and try again.
2020-11-04 00:26:04,951:DEBUG:certbot._internal.log:Exiting abnormally:
Traceback (most recent call last):
  File "/snap/certbot/652/bin/certbot", line 8, in <module>
    sys.exit(main())
  File "/snap/certbot/652/lib/python3.8/site-packages/certbot/main.py", line 15, in main
    return internal_main.main(cli_args)
  File "/snap/certbot/652/lib/python3.8/site-packages/certbot/_internal/main.py", line 1330, in main
    cli_args = snap_config.prepare_env(cli_args)
  File "/snap/certbot/652/lib/python3.8/site-packages/certbot/_internal/snap_config.py", line 67, in prepare_env
    raise e
  File "/snap/certbot/652/lib/python3.8/site-packages/certbot/_internal/snap_config.py", line 57, in prepare_env
    response.raise_for_status()
  File "/snap/certbot/652/lib/python3.8/site-packages/requests/models.py", line 941, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: http://snapd/v2/connections?snap=certbot&interface=content
2020-11-04 00:26:04,951:ERROR:certbot._internal.log:An unexpected error occurred:
2020-11-04 00:26:04,951:ERROR:certbot._internal.log:requests.exceptions.HTTPError: 404 Client Error: Not Found for url: http://snapd/v2/connections?snap=certbot&interface=content

Here more details about the version that might be useful sudo snap version:

snap    2.37.4-1+b1
snapd   2.37.4-1+b1
series  16
debian  10
kernel  4.19.0-11-cloud-amd64

I tried to reinstall snapd (https://snapcraft.io/docs/installing-snap-on-debian) using the last version but still having the same..
Do you guys know what is wrong with my setup and how to fix that?

Thanks

OS: Debian GNU/Linux 9.9 (stretch) x86_64
Kernal: 4.9.0-9-amd64

Hi.

I’m trying to install League of Legends via snap but get this error message:

$ sudo snap install leagueoflegends --edge
error: cannot perform the following tasks:
- Mount snap "leagueoflegends" (35) (cannot find required base "core18")

I cloned the core18 git, but can’t quite figure out how to install it.

I tried installing core18 via snap with this command:
$ sudo snap install core18

But I get this error message:
error: cannot install "core18": invalid snap type: "base"

I then tried to install snapcraft, but was unable to add the repository:
W: The repository 'http://ppa.launchpad.net/snappy-dev/tools/ubuntu eoan InRelease' is not signed.

Are there any easy way to install core18 ?