我无法将 ubuntu 19.10 升级到 20.04 LTS。当我尝试通过终端升级时，输出如下：
salil@salil-latitude-e6430:~$ sudo do-release-upgrade
[sudo] password for salil:
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [1,554 B]
Get:2 Upgrade tool [1,342 kB]
Fetched 1,343 kB in 0s (0 B/s)
authenticate 'focal.tar.gz' against 'focal.tar.gz.gpg'
extracting 'focal.tar.gz'
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Hit http://in.archive.ubuntu.com/ubuntu eoan InRelease
Hit http://in.archive.ubuntu.com/ubuntu eoan-updates InRelease
Hit http://in.archive.ubuntu.com/ubuntu eoan-backports InRelease
Hit http://security.ubuntu.com/ubuntu eoan-security InRelease
Fetched 0 B in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
salil@salil-latitude-e6430:~$
这个问题有解决办法吗？