Thanks Pete for looking up those chat links. I think this is probably the LetsEncrypt issue that's been coming up since Oct 1. https://letsencrypt.org/docs/dst-root-ca-x3-expiration-september-2021/
You likely need to update something on the server. Unfortunately exactly what needs updating seems to vary based on the hosting and several factors.
There is a folder in to which extensions can be downloaded to be used on your site. Some server administrators, us included, prefer to not have any folder 'publically available' for security reasons.
The downsides for the site user is they cannot just grab another extension to try out. The upside is we do not have part of our system potentially vulnerable.
I've been tearing my hair out on this one, attempting a clean CiviCRM install
Same error as above, during install. Clearly something to do with the database, as the install ran for a minute, and produced the error, but no tables were ever written to the database.
I know all requirements are met, as we already have two other running copies of CiviCRM on the ...