denis-anisimov:

This looks like a bug in Spring: spring-projects/spring-boot#27147

JS WebSocket class can't connect to the server and there is nothing to fix on our side.
The same happens with:

• console code ws = new WebSocket("ws://localhost: 35729");
• Live reload Chrome extension: it doesn't work with 2.5.2

pleku:
Fixed in Spring Boot 2.4.9 & 2.5.3

Live reload is broken starting with Spring Boot 2.5.2 #11375
DevTools' LiveReload support's HTTP header handling is case sensitive #26813

ApplicationHome home = new ApplicationHome(MyMainSpringBootApplication.class);
home.getDir();    // returns the folder where the jar is. This is what I wanted.
home.getSource(); // returns the jar absolute path.

How to get spring boot application jar parent folder path dynamically?