Interference with the zlib output compression

[mjkhajeh]

I activated zlib.output_compression from control panel(DirectAdmin) of hosting and this error has shown in my WP:

Notice: ob_end_flush(): failed to send buffer of zlib output compression (1) in /home/****/domains/****/public_html/wp-includes/functions.php on line 5275

Notice: ob_end_flush(): failed to send buffer of zlib output compression (1) in /home/****/domains/****/public_html/wp-includes/functions.php on line 5275

This error is in both frontend and wp dashboad.

I disabled all plugins and change theme to default but it was still the error.

This error causes a great drop in site speed both on the frontend and in the backend. The Query Monitor plugin also reports various slow queries that change as the page refreshes. All of these queries are also common WordPress queries.

[mjkhajeh]

This is an example of slow queries in backend(WP dashboard)