Based on the logs provided, the core issue is that your server restricts the proc_open() function, which JohnCMS currently uses to send emails via the system's local mailer. To fix this, you should switch from the local mailer to SMTP and move email processing to a Cron job.
Open config/constants.php and set USE_CRON to true
Switch the Mail Driver to SMTP
You need to create a local configuration file to override the default mail settings. Create a new file at config/autoload/mail.local.php and paste the following code, replacing the placeholder values with your actual SMTP server details:
<?php
return [
'mail' => [
// Set default transport to smtp
'transport' => 'smtp',
// SMTP Transport settings
'options' => [
'smtp' => [
'name' => 'example.com', // Your domain name
'host' => 'smtp.example.com', // Your SMTP server address
'username' => 'mail@example.com', // Your email login
'password' => 'your_password', // Your email password
'port' => 465, // Port (usually 465 for SSL or 587 for TLS)
'encryption' => 'ssl', // Encryption type (ssl or tls)
],
],
],
];
The reason you are seeing "Internal Server Errors" everywhere is that JohnCMS tries to send emails at the very end of almost every action (registration, posting, or even some downloads).
Since your hosting blocks the proc_open function, the script crashes at the final step. It might even process your data correctly, but it fails to show the page because the mailer cannot start.
To fix this:
Set up SMTP in mail.local.php. This stops the script from using the blocked server function and sends mail through an external provider instead.
Enable Cron in constants.php. This moves the email sending to the background, so the user doesn't have to wait for the mailer to finish, and the page won't crash if the mailer has issues.
Once these two changes are made, the "Internal Server Errors" should disappear because the script will stop calling the forbidden function.
