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WARNING: You are browsing the documentation for Symfony 4.1 which is not maintained anymore. Consider upgrading your projects to Symfony 4.3.

You are browsing the Symfony 4.1 documentation, which changes significantly from Symfony 3.x. If your app doesn't use Symfony 4.1 yet, browse the Symfony 3.4 documentation.

Using webpack-dev-server and HMR

4.1 version

Using webpack-dev-server and HMR

While developing, instead of using yarn encore dev --watch, you can use the webpack-dev-server:

$ yarn encore dev-server

This serves the built assets from a new server at http://localhost:8080 (it does not actually write any files to disk). This means your script and link tags need to change to point to this.

If you're using the encore_entry_script_tags() and encore_entry_link_tags() Twig shortcuts (or are processing your assets through entrypoints.json in some other way), you're done: the paths in your templates will automatically point to the dev server.

You can also pass options to the dev-server command: any options that are supported by the normal webpack-dev-server. For example:

$ yarn encore dev-server --https --port 9000

This will start a server at https://localhost:9000.


This Webpack server is independent from Symfony's development web server and you need to run both separately.

Using dev-server inside a VM

If you're using dev-server from inside a virtual machine, then you'll need to bind to all IP addresses and allow any host to access the server:

$ ./node_modules/.bin/encore dev-server --host --disable-host-check

You can now access the dev-server using the IP address to your virtual machine on port 8080 - e.g.

Hot Module Replacement HMR

Encore does support HMR, but only in some areas. To activate it, pass the --hot option:

$ ./node_modules/.bin/encore dev-server --hot

HMR currently works for Vue.js, but does not work for styles anywhere at this time.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.