Error when connecting to the Nextcloud server: expired certificate (ISRG Root X1Let’sEncrypt)

[Davide Marchi <danjde msw it>]

Hi Friends,

Using Nextcloud 21.0.4 on Debian9/10,
after the last september 2021 server renewal of Let’sEncrypt 
certificate, Gnome Accounts client (Nextcloud) shown the error message 
“Invalid TLS certificate” when we try to add a Nextcloud account.

To the server side we have used “acme.sh” for obtains the certs with the 
option:

--preferred-chain "isrg"

building the chain certs without the X1 ISRG Root certificate, leaving 
the SO client to give it, due to the recent changes made by 
Let'sEncrypt: https://letsencrypt.org/certificates/ --> "We do not use 
the X1, X2, X3, and X4 intermediates anymore."

We have seen that this procedure is working with some clients/servers, 
with official Nextcloud clients, but *not* for Gnome Accounts 
(Nextcloud)!
Please, could you suggest us, if there are other procedures to be 
carried out?

Many thanks!

davide
Italy