Disable zlib.output_compression on WordPress : Notice: ob_end_flush(): failed to send buffer of zlib output compression (1) in /path/wp-includes/functions.php on line 3282 via https://core.trac.wordpress.org/ticket/18525

disable_zlib.output_compression

 SOLUTIONS I have came across so far:

======================== SOLUTION 1 ====================

In plugins (or somewhere) you probably have this code:

ini_set('zlib.output_compression', '1'); 

so, I replaced that code with

if (!is_admin()) ob_start('ob_gzhandler');     //because, in admin pages, it causes plugin installation freezing

and Compression will be remained still ON.

======================== SOLUTION 2 ====================
You may have to use:

remove_action( 'shutdown', 'wp_ob_end_flush_all', 1 );