Stop a plugin in the activation process when a certain WP version is not met then show error message in admin_notices action hook

Question

I have a plugin that I do not want to be activated if it doesn't meet a certain WP version number then show error message in admin_notices action hook. As far as I have researched, the code below is the best that I can achieve this goal:

$wp_version = get_bloginfo('version');
if ( $wp_version < 4.5 ) {
    add_action( 'admin_init', 'deactivate_plugin_now' );
    add_action( 'admin_notices', 'errormsg' ) );
}

public function deactivate_plugin_now() {
    if ( is_plugin_active('myplugin/myplugin.php') ) {
        deactivate_plugins('myplugin/myplugin.php');
    }
}

public function errormsg () {
    $class = 'notice notice-error';
    $message = __( 'Error you did not meet the WP minimum version', 'text-domain' );
    printf( '<div class="%1$s"><p>%2$s</p></div>', $class, $message );
}

But I think I am still doing it wrong because I'm getting the plugin activated message at the same time with the error notice that I assigned.

What would be the proper action hook / filter to properly stop the plugin activation process so I will only get the error message?

Answer 1

I may be late to this party, but to stop plugin activation and have WordPress show an error message where the admin notices go, I simply output an error message and terminate execution. This has the added advantage of playing nice with wp-cli:

Example:

class testPlugin() {

  ...

   static function activate() {

   //[do some stuff here]

   if ($error) {
      die('Plugin NOT activated: ' . $error);
   }

}

register_activation_hook( __FILE__, array( 'testPlugin', 'activate' ));

Answer 2

Essentialy, you can not do it the way you want. All wordpress form are redirecting after completing their process and do not generate output by themself and therefor the error message is generated on a different page request. If your plugin will not be active at that point, there will be no message displayed. Further complication is that plugins might be activated by Ajax.

An ugly but working way is to fail the activation by generating an php error, or IIRC any output will do, so you can just output something like "version mismatch" in the plugin activation hook, which will be displayed in the error output box that is being displayed when activation fails.

Something to think about: people might include your plugin files, or somehow activate it forcefully by bypassing the UI, or using wp-cli. depending on the reasons you want to fail the activation, just having the error message might be better than trying to fail the activation

Answer 3

How about this code to suppress hello.php (Hello Dolly) if WP < 8.5:

 add_action( 'activate_plugin', '_20170113_superess_activate' , 10, 2);

 function _20170113_superess_activate($plugin, $network_wide){
      global $wp_version;

      if ( $wp_version < 8.5 && 'hello.php' == $plugin ) {
        error_log( 'WordPress need to be at least 8.5' );      
        $args = var_export( func_get_args(), true );
        error_log( $args );
        wp_die( 'WordPress need to be at least 8.5 to activate this plugin' );
      }
 }

I think this is good because it doesn't force you to create admin notices. You will simply get the feedback about the reason for abortion of the plugin install.

I added this code for HelloDolly, but you will need to adjust.

Answer 4

Since you updated the title I need to provide the another answer, the previous one please don't ignore because it is even more simple than this one.

add_action( 'admin_notices', 'my_plugin_admin_notices' );

function my_plugin_admin_notices() {
    if ( ! is_plugin_active( 'hello.php' ) && isset( $_GET['customhello'] ) ) {
        echo '<div class="error"><p>WordPress need to be at least 8.5 to activate this plugin</p></div>';
    }
}

add_action( 'activate_plugin', '_20170113_superess_activate', 10, 2 );

function _20170113_superess_activate( $plugin, $network_wide ) {
    global $wp_version;
    if ( $wp_version < 8.5 && 'hello.php' == $plugin ) {
        $redirect = self_admin_url( 'plugins.php?customhello=1' );
        wp_redirect( $redirect );
        exit;
    }
}

Please note that when you try to activate the plugin you interact with plugins.php file. In there you have a big switch of actions that you can run.

And in case you have the error set $_GET['error'] at the moment you have just the predefined error messages — you cannot create your own custom message. This is why I proposed you the solution like this.

One may propose the custom messages as admin notices to the WordPress core in cases plugins do not meet some requirements.

Answer 5

I know I am too late to post the reply on this but it may help someone. You could just unset the $_GET variable which triggers the message:

$wp_version = get_bloginfo('version');
if ( $wp_version < 4.5 ) {
    add_action( 'admin_init', 'deactivate_plugin_now' );
    add_action( 'admin_notices', 'errormsg' ) );
}

public function deactivate_plugin_now() {
    if ( is_plugin_active('myplugin/myplugin.php') ) {
        deactivate_plugins('myplugin/myplugin.php');
        unset($_GET['activate']);
    }
}

public function errormsg () {
    $class = 'notice notice-error';
    $message = __( 'Error you did not meet the WP minimum version', 'text-domain' );
    printf( '<div class="%1$s"><p>%2$s</p></div>', $class, $message );
}