Upgrade ubuntu 18 to 20, apt error stops upgrade

[guiverc]

I’ll refer you to the Support and Help section guide where you’ll note

@ian-weisser

• Only official flavors of Ubuntu are supported here. “Based on” Ubuntu is not close enough, sorry.
• Your question should clearly state which standard-supported version of Ubuntu you are using and which official flavor .
• Specify the version using proper yy.mm versioning, where mm should be either 04 or 10 as we release in April and October. Just using the yy (i.e. 24 or 22) is imprecise.

The oldest release of Ubuntu in standard support currently is Ubuntu 22.04 LTS from 2022-April, which is still in it’s 5 years of standard support.

Ubuntu Core 18 & Ubuntu Core 20 are supported now only by Canonical; the five years of standard support having completed (Canonical support it for a total of 10 years).

If you meant Ubuntu 20.04 LTS; it’s EOSS too with ESM starting on 29 May 2025…