The error happens right after publishing a new post. people will start getting the error message (ERR_HTTP2_PROTOCOL_ERROR) on their browsers and this happens on all devices. after waiting for sometimes upto 10 minutes the error will disappear the site becomes accessible. The site supports HTTP2 (We are using wordpress).
But as admin logged-in I can see the frontend of the site when others are getting the error.
This does not happen when cache is disabled.