Http error 500 - GLPI version 9.5.6

[aureliefaci]

On the 9.5.6 version of GLPI it is impossible to activate the plugin > crash with HTTP Error 500
I had to delete the plugins to make it work again.

[RogelioBlancoP]

I am having the same issue.

Error log says that "vendor" folder and its content (autoload.php) is missing:

[Thu Dec 02 12:11:45.813440 2021] [php7:warn] [pid 127] [client 172.24.0.1:45874] PHP Warning: require_once(/var/www/html/glpi/plugins/fpsaml/inc/../vendor/autoload.php): failed to open stream: No such file or directory in /var/www/html/glpi/plugins/fpsaml/inc/main.class.php on line 9
[Thu Dec 02 12:11:45.813471 2021] [php7:error] [pid 127] [client 172.24.0.1:45874] PHP Fatal error: require_once(): Failed opening required '/var/www/html/glpi/plugins/fpsaml/inc/../vendor/autoload.php' (include_path='.:/usr/share/php') in /var/www/html/glpi/plugins/fpsaml/inc/main.class.php on line 9