Error includes/api/external.php on line 31

Hello,

I’ve installed plugin and on the first admin site plugin show this:

Warning: Cannot modify header information – headers already sent by (output started at /wp-content/plugins/newstatpress/includes/api/nsp_api_overview.php:101) in /wp-content/plugins/newstatpress/includes/api/external.php on line 31

Any solution to the problem

regards

Paweł

https://wordpress.org/plugins/newstatpress/