Cannot modify header information – pluggable.php

Have you checked every item here?:

https://codex.www.ads-software.com/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F

Ok, after editing the config file, the error has now changed to:

Strict Standards: Redefining already defined constructor for class googlefonts in /home/printet1/public_html/wp-content/plugins/wp-google-fonts/google-fonts.php on line 140 Warning: Cannot modify header information – headers already sent by (output started at /home/printet1/public_html/wp-content/plugins/wp-google-fonts/google-fonts.php:140) in /home/printet1/public_html/wp-includes/pluggable.php on line 913

Line 140 is affecting multiple lines in the pluggable.php.

The coding on line 140-168 is:

function __construct(){
            //Language Setup
            $locale = get_locale();
            $mo = dirname(__FILE__) . "/languages/" . $this->localizationDomain . "-".$locale.".mo";
            load_textdomain($this->localizationDomain, $mo);

            //"Constants" setup
            $this->thispluginurl = WP_PLUGIN_URL . '/' . dirname(plugin_basename(__FILE__)).'/';
            $this->thispluginpath = WP_PLUGIN_DIR . '/' . dirname(plugin_basename(__FILE__)).'/';

            //Initialize the options
            //This is REQUIRED to initialize the options when the plugin is loaded!
            $this->getOptions();

			//Load the list of fonts from the Google API or local cache
            $this->gf_fonts = get_option($this->gf_data_option_name);

			//Convert the options from pre v3.0 array
			$this->gf_convert_fonts();

            //Actions
            add_action("admin_menu", array(&$this,"admin_menu_link"));
            add_action('admin_enqueue_scripts',array(&$this,'gf_admin_scripts'));

			add_action('wp_enqueue_scripts',array(&$this, 'googlefontsstart'));
			add_action("wp_head", array(&$this,"addgooglefontscss")); 

			add_action('wp_ajax_googlefont_action', array($this, 'googlefont_action_callback'));
        }

Any advice on how to fix this? I feel I’m a bit out of my league on this one.

Also, thank you very much for the link, it was helpful in understanding more about the issue.

Solved the problem!

For others’ reference:

https://www.ads-software.com/support/topic/error-message-on-wp-google-fonts-plugin-activation-with-wp-version-371?replies=2

Thank you very much for your help, it definitely made working through this problem easier.

I fixed this by removing

<?php flush(); ?>

from my header.php file