Roundcube suddenly fails for all users

This is from the logs:

*336 FastCGI sent in stderr: "PHP message: PHP Warning:  require_once(/var/lib/roundcube/vendor/composer/autoload_real.php): Failed to open stream: No such file or directory in /var/lib/roundcube/vendor/autoload.php on line 10
PHP message: PHP Fatal error:  Uncaught Error: Failed opening required '/var/lib/roundcube/vendor/composer/autoload_real.php' (include_path='/var/lib/roundcube/program/lib:.:/usr/share/php') in /var/lib/roundcube/vendor/autoload.php:10
Stack trace:
#0 /var/lib/roundcube/program/include/iniset.php(64): require()
#1 /var/lib/roundcube/index.php(40): require_once('...')
#2 {main}
  thrown in /var/lib/roundcube/vendor/autoload.php on line 10" while reading response header from upstream, client: xx.xxx.xxx.xxx, server: webmail.xxx.xxx, request: "GET / HTTP/2.0", upstream: "fastcgi://127.0.0.1:9000", host: "webmail.xxx.xxx"
2023/05/11 17:55:55 [error] 15827#15827: *397 FastCGI sent in stderr: "PHP message: PHP Warning:  require_once(/var/lib/roundcube/vendor/composer/autoload_real.php): Failed to open stream: No such file or directory in /var/lib/roundcube/vendor/autoload.php on line 10PHP message: PHP Fatal error:  Uncaught Error: Failed opening required '/var/lib/roundcube/vendor/composer/autoload_real.php' (include_path='/var/lib/roundcube/program/lib:.:/usr/share/php') in /var/lib/roundcube/vendor/autoload.php:10

Somehow composer was no longer installed? Or removed? Or suddenly required by RC ?
No idea. This is a pretty default debian 11 install…

Had to remove the /var/lib/roundcube/vendor dir and do
# apt install composer
and in the /var/lib/roundcube dir run
# composer install

Please advice if this would suffice… It said I should not install composer using root, is that going to be an issue?

Rouncube download comes with the vendor folder…

Make sure the permissions are:
root www-data

and it should be fine