comprehensive guide to fix connection lost error in wordpress

At first, I thought there was something wrong with my activated plugins, themes updating and changing to default themes, downgrading the version of WordPress and everything and the error still occurs.   Basically, the admin-ajax php is used to make AJAX based connections to the server, directly from your browser.   It works in the background to send regular pulse between the browser and the server that is repeated at regular intervals and can be used to keep them sync, allowing near-real-time frontend updates..   I found that message is result of your server throwing error and WordPress Heartbeat API catching that error..   The purpose of this API is to simulate connection between the browser and the server.   The idea is to have API that sends XHR requests to the server every 15 seconds and triggers events on receiving data.   Disable WordPress Heartbeat API Disable everywhere..   There are lot of plugins on WordPress Plugins Repository that helps you change or disable WordPress Heartbeat values..   Controlling WordPress Heartbeat API with plugin Disable WordPress Heartbeat API Using the Code.   This happens so it responds with error.   Read more