Why ‘Are you authorized to profile this page? No probe response, missing PHP extension or invalid signature for relaying agent’ issue comes after installation of blackfire?

On successful installation of blackfire we will get below message after running

 sudo apt-get install blackfire-php

message → “Please restart your Web server(s) or PHP-FPM to complete installation”.

-Either we skip to restart web browser or PHP-FPM.

-Or web browser’s version not compatible.