Spring Boot 1.x had the transitive dependency spring-boot-starter-web whenever one of the following template engine starters was used:

• spring-boot-starter-freemarker
• spring-boot-starter-thymeleaf
• spring-boot-starter-mustache

This was done because Spring Web MVC was running on top of the Servlet API, which is the only web application framework that was available at that time.

Now, with the introduction of the Spring Reactive Web starter spring-boot-starter-webflux, which is completely independent of the Servlet API, transitive dependencies from those template engine starters have been removed. This means that, when a template engine starter dependency is added, a developer needs to manually add a dependency to either Spring Web MVC starter or Spring Web Flux starter based on the requirement.