version: 2024.06

Roundcube throws a server error when trying to add more than one attachment. The logs show the following message:
"upstream sent too big header while reading response header from upstream."

I resolved the issue by adding the following entries to nginx-webmail.conf:

        # fastcgi buffers for php-fpm #
        fastcgi_buffers 16 32k;
        fastcgi_buffer_size 64k;
        fastcgi_busy_buffers_size 64k;

I noticed that similar entries were added after #3272, but later removed in commit 8ea66c2.
While that may have fixed SnappyMail as the commit claims, it seems to have broken Roundcube again.
Setting only
fastcgi_request_buffering off
is not sufficient for Roundcube.