当我尝试使用 do-release-upgrade 从 Ubuntu 18.04 LTS 升级到 20.04 LTS 时，遇到了以下错误：
####################################################################
"You have the package lxd installed but your system is unable to reach
the Snap Store. lxd is now provided via a snap and the release
upgrade will fail if snapd is not functional. Please make sure you're
connected to the Internet and update any firewall or proxy settings
's needed so that you can reach api.snapcraft.io. If you are ar
enterprise with a firewall setup you may want to configure a Snap
store proxy.
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
;ommand detached from window (Sun Apr 21 13:32:00 2024) ===
=== Command terminated with exit status 1 (Sun Apr 21 13:32:10 2024) ==="
#######################################################################
# snap refresh
error: cannot refresh: Post https://api.snapcraft.io/v2/snaps/refresh: read tcp
10.10.*.*:50822->185.125.188.58:443: read: connection reset by peer
oot@gss-zabbix:/tmp/ubuntu-release-upgrader-v1j355nO# snap refresh snapc
rror: cannot refresh "snapd": Post https://api.snapcraft.io/v2/snaps/refresh: read tcr
10.10.*.*:54972->185.125.188.55:443: read: connection reset by peer