Bon, j’ai toujours (de nouveau) pas les bonnes permissions !!
/var/www/roundcube# ls -l
total 2336
drwxr-xr-x 2 root root 4096 Feb 18 2021 bin
-rw-r--r-- 1 root root 186666 Feb 8 2021 CHANGELOG
-rw-r--r-- 1 root root 1238 Feb 18 2021 composer.json
-rw-r--r-- 1 root root 943 Feb 8 2021 composer.json-dist
-rw-r--r-- 1 root root 33032 Feb 18 2021 composer.lock
-rwxr-xr-x 1 root root 1996311 Feb 18 2021 composer.phar
drwxr-xr-x 2 root root 4096 Feb 18 2021 config
-rw-r--r-- 1 root root 12843 Feb 8 2021 index.php
-rw-r--r-- 1 root root 12864 Feb 8 2021 INSTALL
drwxr-xr-x 3 root root 4096 Feb 18 2021 installer
-rw-r--r-- 1 root root 4087 Feb 8 2021 jsdeps.json
-rw-r--r-- 1 root root 35147 Feb 8 2021 LICENSE
drwxr-xr-x 2 roundcube roundcube 4096 Feb 18 2021 logs
drwxr-xr-x 39 root root 4096 Feb 8 2021 plugins
drwxr-xr-x 8 root root 4096 Feb 8 2021 program
drwxr-xr-x 3 root root 4096 Feb 18 2021 public_html
-rw-r--r-- 1 root root 3810 Feb 8 2021 README.md
-rw-r--r-- 1 root root 26 Jul 24 2016 robots.txt
drwxr-xr-x 5 root root 4096 Feb 8 2021 skins
drwxr-xr-x 7 root root 4096 Feb 8 2021 SQL
drwxr-xr-x 3 roundcube roundcube 28672 Jul 15 18:11 temp
-rw-r--r-- 1 root root 4148 Feb 8 2021 UPGRADING
drwxr-xr-x 9 root root 4096 Feb 18 2021 vendor
crotte alors !!!