The excursion booking site shows “Error 500” on every page

Kasbah Tours (a fictional agency offering excursions into the desert and the Draa valleys) sells its tours on www.kasbahtours.ma, a PHP site hosted on a single EC2 instance (web-kasbah-01, Amazon Linux 2023, nginx + PHP-FPM).

For security, port 22 is closed: the instance is administered only through AWS Systems Manager (Session Manager). On Friday, the contractor applied the system updates.

This morning, customers who want to book this week's excursion see “Error 500”. You have opened a session with aws ssm start-session --target i-0d3f5a7c9e1b24680: the commands below run on the instance (user ssm-user, with sudo). The instance has the AWS CLI and a read-only role on EC2.