We are using Mailjet for email subscriptions on our website. We use a widget in the header, footer and on a subscriptions page. These had been working quite well for the last year, but something must have changed during the last upgrade.

The redirect to a page telling user to check email post email submission is no longer working. And because of that a confirmation email is not arriving properly. Opened a ticket at support, but had no answer yet and I was hoping some WordPress developers here see the issue. It seems that the custom email template

<?php

use MailjetPluginIncludesMailjeti18n;

?>

<!-- This file is used to markup the public-facing widget. -->
<div class="mailjet_widget_front_container">
    <?php
    extract($args);

    $locale = Mailjeti18n::getLocale();
    $language = Mailjeti18n::getCurrentUserLanguage();

    // Check the widget options
    $title = isset($instance[$locale]['title']) ? apply_filters('widget_title', $instance[$locale]['title']) : '';
    $emailLabel = !empty($instance[$locale]['language_mandatory_email']) ? apply_filters('widget_language_mandatory_email', $instance[$locale]['language_mandatory_email']) : Mailjeti18n::getTranslationsFromFile($locale, 'your@email.com');
    $buttonLabel = !empty($instance[$locale]['language_mandatory_button']) ? apply_filters('widget_language_mandatory_button', $instance[$locale]['language_mandatory_button']) : Mailjeti18n::getTranslationsFromFile($locale, 'Subscribe');
    ?>
    <div class="widget-text wp_widget_plugin_box">

        <!--Widget title-->
        <div>
            <span style="font-size: 12px;">
                <?php
                    do_action('before_title_widget_mailjet');
                    echo $before_title . $title . $after_title;
                    do_action('after_title_widget_mailjet');
                ?>
            </span>
        </div>
        <!--End Widget title-->

        <!--Widget form-->
        <form method="post" action=" <?php echo esc_url($_SERVER['REQUEST_URI']) ?>" id="mjForm" name="<?php echo $widget_id ?>">

            <!--Subscription email input(mandatory)-->
            <div class="input-group" style="margin-bottom: 10px!important">
                <input type="email" name="subscription_email" id="mailjet_widget_email" required="required" placeholder="* <?php echo $emailLabel ?>">
                <input type="hidden" name="subscription_locale" id="mailjet_widget_locale" value="<?php echo $locale ?>">
            <!-- </div> -->
            <?php

            // Check for the additional properties from the admin advanced settings
            for ($i = 0; $i < 5; $i++) {

                if(!isset($instance[$locale])) {
                    continue;
                }

                // Property id - '0' there is no selected property
                $contactPropertyId = (int)$instance[$locale]['contactProperties' . $i];

                // Skip if this property is not added in admin part
                if (empty($contactPropertyId)) {
                    continue;
                }

                if(empty($this->propertyData[$contactPropertyId])) {
                   continue;
                }

                // Mailjet property type
                $propertyDataType = $this->propertyData[$contactPropertyId]['Datatype'];

                // Map mailjet property type to valid input type
                $inputType = $this->getInputType($propertyDataType);


                // The value of the label
                $placeholder = $instance[$locale][$language . 'Label' . $i];

                // '0' - optional
                // '1' - mandatory
                // '2' - hidden
                $propertyType = (int) $instance[$locale]['propertyDataType' . $i];

                // Display block by default
                $display = 'block';

                // Not required by default
                $required = '';

                // Used on hidden properties
                $value = '';

                $requiredStar = '';

                // Set required, display and value depends on the current property type
                switch ($propertyType) {
                    // Optional input
                    case 0:
                        // Display: block
                        // No value, only placeholder
                        // Not Required
                        break;
                    // Mandatory input
                    case 1:
                        // Display: block
                        // No value, only placeholder

                        // Required
                        $required = 'required';

                        // Add * to placeholder to indicate that the input is required
                        $requiredStar = '* ';
                        break;
                    // Hidden input
                    case 2:
                        // Display: none
                        $display = 'none';

                        // Value is given from admin advanced settings
                        $value = 'value="'.$placeholder.'"';
                        break;
                }
                $class = '';
                if ('date' === $inputType) {
                    $class = 'mjDate';
                }

                // Boolean type is checkbox
                if ('bool' === $inputType) {
                    ?>
                    <div class="input-group input-group-sm" style="margin-bottom: 10px!important">
                        <input type="checkbox" <?php echo $required ?> name="properties[<?php echo $contactPropertyId ?>]" id="mailjet_property_<?php echo $i ?>" <?php echo $value ?> />
                        <label for="mailjet_property_<?php echo $i ?>" 
                            style="text-decoration: appworkspace;margin-bottom: 20px!important;font-weight: 500!important;display: inline!important;cursor: pointer;">
                            <?php echo $requiredStar.$placeholder ?>
                        </label>
                    </div>
                    <?php
                } else {
                ?>
                <div class="input-group input-group-sm" style="margin-bottom: 10px!important">
                    <input <?php echo $required ?> type="text" class="mj_form_property <?php echo $class ?>" 
                    name="properties[<?php echo $contactPropertyId ?>]" <?php echo $value ?> 
                    placeholder="<?php
                    echo $requiredStar;
                    echo $placeholder
                    ?>" style="display: <?php echo $display ?>">
                </div>
                <?php
                }
            }
            ?>
                <input type="hidden" name="widget_id" value="<?php echo $widget_id ?>">
              <!-- <input type="submit" value="<?php // echo $buttonLabel ?>"> -->
                <span class="input-group-btn">
                  <button type="submit" value="<?php echo $buttonLabel ?>" name="submit" id="submit" class="btn btn-default">
                  <i class="fa fa-circle"></i>
                </button>
                </span>
            </div>
        </form>
        <?php
        if (!empty($form_message[$widget_id])){
            // echo '<span class="mailjet_widget_form_message">'. $form_message[$widget_id] .'</span>';
            $page = get_page_by_title('Email Sent');
            // print_r($page);
            wp_redirect(get_permalink($page->ID));
            exit;
        }
        ?>
    </div>
</div>

at site/web/app/themes/sage/templates/custom_mailjet_widget_template.php is no longer working properly. The redirect used

$page = get_page_by_title('Email Sent');
// print_r($page);
wp_redirect(get_permalink($page->ID));
exit;

worked well before.

If I do not load the custom template with :

add_filter( 'mailjet_widget_form_filename',  __NAMESPACE__ . 'useMailjetCustomWidgetFormTemplate' );
function useMailjetCustomWidgetFormTemplate($templatePath) {
    return get_template_directory() . '/templates/custom_mailjet_widget_template.php';
}

all works. But I then loose styling and the redirect. I do prefer to use it as this is the only way to do the redirect. So my question is, has anything changed with the way widgets work recently that could cause the above code not to work? Two, any ideas how to do this better and make it work?