Display an error message in the admin panel if a plugin is not activated in WordPress

Display error if a plugin is not installed

Displaying an error message when a required plugin is not installed is a useful way to inform users about missing features and encourage them to install the necessary plugin. By following the code outlined below, you can easily add this functionality to your WordPress website.

<?php
add_action('admin_notices', 'my_plugin_error_notice');

function my_plugin_error_notice()
{
    if (!is_plugin_active('plugin-directory/plugin-main-file.php')) : ?>
        <div class="error">
            <p>The required plugin is not installed. Please install the plugin to use this feature.</p>
        </div>
    <?php
    endif;
}

Display error message if ACF is not installed

ACF (Advanced Custom Fields) is a popular WordPress plugin that allows users to easily create custom fields and add them to posts, pages, and custom post types. ACF is a user-friendly and flexible plugin that enables users to create complex custom fields without having to write any code.

To check if the ACF plugin is installed on a WordPress website, you can use the following code.

<?php

add_action('admin_notices', 'display_acf_error_if_not_installed');

function display_acf_error_if_not_installed()
{
    if (!is_plugin_active('advanced-custom-fields/acf.php') && !is_plugin_active('advanced-custom-fields-pro/acf.php')) : ?>
        <div class="error">
            <p>The required plugin is not installed. Please install the plugin to use this feature.</p>
        </div>
    <?php
    endif;
}

This code can help you ensure that your custom code or plugin will work properly with ACF installed, and can provide a fallback solution if ACF is not installed.