Error - the add on downloaded from this site could not be installed because it appears to be corrupt old version

[rag_gupta (Rag)]

I’ve Firefox 55 & 72 version Firefox on Ubuntu and I could install new private released addon versions but since this week it giving this “corrupt” message .

However it is able to install existing addon versions(released before this week) but not the newer versions released from this week onwards.

What is this strange issue?

[juraj.masiar]

Signing certificates used in addons/browsers have some expiration time, so they need to be updated regularly.
For example, from the release notes of Firefox ESR 115.13.0:

The root certificate used to verify add-ons and signed content has been renewed to avoid upcoming expiration.

Also, old addons had to be re-signed recently:

Upgraded add-on signatures

Hello Add-on Creators! I wanted to highlight some points from a recent email we sent out regarding Mozilla upgrading the signing for Firefox add-ons to provide a stronger signature for a more secure add-ons ecosystem. All add-ons submitted to https://addons.mozilla.org (AMO) after April 5, 2019 are not impacted by the upgraded signing, regardless if they are hosted on AMO or if they are self-distributed. [no action required] All add-ons submitted to AMO prior to April 5, 2019 that are hosted …

Note that using old browser without security fixes is super dangerous, even in Linux.
See for example bugs from Pwn2own event:

Mozilla fixes two Firefox zero-day bugs exploited at Pwn2Own

An attacker was able to inject an event handler into a privileged object that would allow arbitrary JavaScript execution in the parent process.

[rag_gupta (Rag)]

I deleted all cert8.db files as mentioned in https://support.mozilla.org/en-US/questions/781004

However does not work

[hans_squared]

@rag_gupta

I’ve Firefox 55 & 72 version Firefox on Ubuntu

Why are you still using FF versions from 2017 and 2020 ?
(and why two old versions, instead of an old one, and a current one)
Is your Ubuntu at least up-to-date?

[rag_gupta (Rag)]

One old autofill extension works in old versions of Firefox. I’m happy about it.

So what I’m asking how to refresh those certificate expiry time in the browser given that I’ve blocked this domain aus5.mozilla.org(in /etc/hosts) so that Firefox not update itself to latest version automatically ?