getMailer gives "Failed to start application" exception after updating to Joomla4, how do I fix it?

Question

The issue

Quoting (again) from an old question of mine:

I have a form in my Joomla! site. Once completed, the form should send an e-mail but only if some conditions have been met.

Not having been able to use standard, commercially available mailers while also checking those conditions, I am using jQuery.ajax to POST the content of the form to a custom PHP page that uses Factory::getMailer to actually send the e-mail.

Maybe it's convoluted, but it works.

After updating the site from Joomla3 to Joomla4, it stopped working.

The code is the exact same as in this question I posted a while ago:

//_JEXEC must be 1 or require_once requests will fail because of their "_JEXEC or die"
define('_JEXEC', 1);

//Then I need to require some Joomla! files where getMailer is defined
define('JPATH_BASE', __DIR__);
require_once (JPATH_BASE.'/includes/defines.php');
require_once ('includes/framework.php');

try {
    //fetching variables from querystring
    $name=$_POST['name'];
    $body=$_POST['body'];
    $from=$_POST['from'];
    //invoke mailer
    $mail = \Joomla\CMS\Factory::getMailer();
    $mail->setSender('[email protected]');
    $mail->addRecipient('[email protected]');
    $mail->setFrom($from,$name); # who is it?
    $mail->addReplyTo($from,$name); # who do I reply to?
    $mail->setSubject('E-mail from Firefighter\'s form');
    $mail->setBody($body);
    $mail->ClearCCs();
    $mail->ClearBCCs();
    $mail->ClearAttachments();
    $mail->ClearCustomHeaders();
    $mail->Send();
    echo "Mail sent";
    exit;
}
catch (Exception $e) {
    echo $e->getMessage();
}

Some considerations:

• I restored a Joomla3 backup and it works, so I don't think it is a problem with PHPmailer versions
• I have checked with the hosting and they are not blocking any e-mails this time (last time, they were the cause of the problem)

---

Testing and debugging

• I have had the host activate php debugging and it doesn't log anything.
• I have activated Joomla4's maximum level of error reports and nothing shows up.
• I have placed an echo command right before Send(), and I get that right before the "failed to start application" from the catch echo.
• Commenting out $mail->Send(); and nothing else echoes "Mail sent", as expected (of course, the mail is not sent).
• Joomla's test e-mail works correctly.

So, everything works properly but the Send() function

---

I have not had time yet to check the following:

Just before the catch structure:

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

Adding $mail->isHtml(true);

Adding $mail->SMTPDebug = 2; (or 3)

---

I don't know if it's related to my problem (after all, I have not changed those settings in the last few weeks) but here are the settings, translated back from my language:

E-mail sending: yes Disable user e-mail sending: no Email from: [the mail I use for ftp access] Sender name: Firefighter's company's page Reply to e-mail: Reply to name: E-mail function: PHP mail

The question

How do I make my mailer work again?

Answer 1

The "Failed to start application" exception is thrown by \Joomla\CMS\Factory::getApplication(), which is called by \Joomla\CMS\Mail\Mail::Send()

The problem is because the appliocation object has not been set within the Factory.

The code that you have used to initiate a Joomla application works for version 3, but needs to be updated for version 4

Replace the code before your try/catch block with the following block and the script should work. (Code taken and stripped down from <JoomlaRoot>/index.php and <JoomlaRoot>/includes/app.php)

define('_JEXEC', 1);
define('JPATH_BASE', __DIR__);
require_once JPATH_BASE . '/includes/defines.php';
require_once JPATH_BASE . '/includes/framework.php';

$container = \Joomla\CMS\Factory::getContainer();
$container->alias('session.web', 'session.web.administrator')
    ->alias('session', 'session.web.administrator')
    ->alias('JSession', 'session.web.administrator')
    ->alias(\Joomla\CMS\Session\Session::class, 'session.web.administrator')
    ->alias(\Joomla\Session\Session::class, 'session.web.administrator')
    ->alias(\Joomla\Session\SessionInterface::class, 'session.web.administrator');

$app = $container->get(\Joomla\CMS\Application\AdministratorApplication::class);

\Joomla\CMS\Factory::$application = $app;