belated note: I'm running Firefox on Ubuntu 26.04, using the default snap. (Pic related.)

I don't think the problem is localized there, though, because when I went a-web-searchin' I saw MANY similar complaints about Ajax and FF dating back nearly 20 years.

On a suggestion from someone who says they have no issues with Roundcube under Debian FF ESR, I tried installing from Mozilla's Apt repository.

No obvious change, sadly. Still gets stuck on "refreshing" and fails to update.

@oemb1905 it's not server side because it's the same server, same network path, and same workstation on the client side as well. Literally the only change is the browser.

If you've got some other answer than ajax I'm listening, but to the best of my understanding ajax is the way RC keeps a live two-way connection going WITH the server.

What am I missing?

@jimsalter I had an issue only with one account, which was an email address that gets thousands per day (for fail2ban reports). All other accounts worked flawlessly under Firefox, including the PWA extension. For that one, though, I had to beef up dovecot in 10-master.conf as follows:

service imap {
vsz_limit = 4096M
process_limit = 2048
}

Then, similarly in /etc/dovecot/conf.d/20-imap.conf, I had to add/replace:

protocol imap {
imap_max_line_length = 256k
mail_max_userip_connections = 50
imap_idle_notify_interval = 15s
}

This fixed the red bar you get where it says fail to connect. Once that was gone, I can leave the tab (or PWA) open indefinitely and mail just comes in no issue. I only use Firefox for checking Roundcube. My full email server setup is here:

https://wiki.haacksnetworking.org/doku.php?id=computing:mailserver-trixie

Keep me posted and hope you get it sorted. But yeah, I'm kind of neurotic about email so I would certainly notice if it failed to refresh, provide alerts, or function - can't recreate here, but I certainly trust that you are not getting the same results ;(