Hello,
Thank you very much for your contribution to make this product more useful.

Thanks

I just downloaded this plugin today and I’m getting the same error.

Warning: A non-numeric value encountered in /<path-to-wp-install>/wp-includes/media.php on line 647 Warning

This error is shown on profile page in WP Admin on my installation.

Open the file

/wp-content/plugins/wp-user-avatar/includes/class-wp-user-avatar-functions.php

Then look for the function

public function wpua_get_avatar_original($id_or_email=””, $size=””, $default=””, $alt=””)

and exchange the code with this:

public function wpua_get_avatar_original($id_or_email="", $size="", $default="", $alt="") {
    global $avatar_default, $mustache_avatar, $wpua_avatar_default, $wpua_disable_gravatar, $wpua_functions;
    // Remove get_avatar filter
    remove_filter('get_avatar', array($wpua_functions, 'wpua_get_avatar_filter'));
    if((bool) $wpua_disable_gravatar != 1) {
      // User doesn't have Gravatar and Default Avatar is wp_user_avatar, show custom Default Avatar
      if(!$wpua_functions->wpua_has_gravatar($id_or_email) && $avatar_default == 'wp_user_avatar') {
        // Show custom Default Avatar
        if(!empty($wpua_avatar_default) && $wpua_functions->wpua_attachment_is_image($wpua_avatar_default)) {
         // $wpua_avatar_default_image = $wpua_functions->wpua_get_attachment_image_src($wpua_avatar_default, array($size,$size));
			$size_numeric_w_x_h = array( get_option( $size . '_size_w' ), get_option( $size . '_size_h' ) );	
			$wpua_avatar_default_image = $wpua_functions->wpua_get_attachment_image_src($wpua_avatar_default, $size_numeric_w_x_h);	
	 
          $default = $wpua_avatar_default_image[0];
        } else {
          $default = $mustache_avatar;
        }
      } else {
        // Get image from Gravatar, whether it's the user's image or default image
        $wpua_image = get_avatar($id_or_email, $size);
        // Takes the img tag, extracts the src
        $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $wpua_image, $matches, PREG_SET_ORDER);
        $default = !empty($matches) ? $matches [0] [1] : "";
      }
    } else {
      if(!empty($wpua_avatar_default) && $wpua_functions->wpua_attachment_is_image($wpua_avatar_default)) {
//      $wpua_avatar_default_image = $wpua_functions->wpua_get_attachment_image_src($wpua_avatar_default, array($size,$size));
				$size_numeric_w_x_h = array( get_option( $size . '_size_w' ), get_option( $size . '_size_h' ) );
				$wpua_avatar_default_image = $wpua_functions->wpua_get_attachment_image_src($wpua_avatar_default, $size_numeric_w_x_h);

        $default = $wpua_avatar_default_image[0];
      } else {
        $default = $mustache_avatar;
      }
    }
    // Enable get_avatar filter
    add_filter('get_avatar', array($wpua_functions, 'wpua_get_avatar_filter'), 10, 5);
    /**
     * Filter original avatar src
     * @since 1.9
     * @param string $default
     */
    return apply_filters('wpua_get_avatar_original', $default);
  }

This bug is still not fixed, even though a solution was provided?

Is that bugfix only included in the Pro version?

it is still not fixed!