The client cannot connect to the /__webpack_hmr endpoint

[koistya]

No error messages. How to debug this issue?

[glenjamin]

What version of express are you using?
http://expressjs.com/4x/api.html#req.path should exist.

There's been a few issues with the eventsource polyfill - i'm going to revert those changes and unpublish 2.0.1 for now. Can revisit it with more testing.

[glenjamin]

v2.0.1 has been marked deprecated and v2.0.2 released without the eventsource polyfill dfb7efb

[koistya]

@glenjamin don't you want to keep it working with non Express servers? E.g. when you need to launch a dev server by using BrowserSync (which uses Connect under the hood).

[glenjamin]

@koistya - I do want to work with non-express servers - yes!

I've closed this PR because the same change was made in dfb7efb

[koistya]

Thanks! 2.0.2 works fine with BrowserSync now

[hoodsy]

Without webpack running in my project, I consistently see requests to __webpack_hmr:

GET /__webpack_hmr 200 1.254 ms - 2092
GET /__webpack_hmr 200 3.087 ms - 2092
GET /__webpack_hmr 200 2.264 ms - 2092

When running my express server on a different port than what was used for my project using webpack, I can avoid these requests. They don't actually affect my project, but are extremely annoying. Is webpack_hmr running in the background? Is there a way to prevent this?
@glenjamin

[glenjamin]

If you have the client in your bundle, it will continuously attempt to connect to the server. If you want to remove the client, you need to leave it out of the client bundle.

[travisbmiller]

@glenjamin I know this is a little old but I am having the same problem @hoodsy is asking about. my my backend API are not bundle with client but stilling seeing the request to _webpack_hmr. You you help me understand what you mean by "If you want to remove the client, you need to leave it out of the client bundle."

Thanks

[glenjamin]

@travisbmiller in your webpack config there's a line which adds the hot-middleware client to the bundle. If you leave this out, it won't attempt to connect to the server

[travisbmiller]

@glenjamin Thanks for the response. I removed it 'webpack-hot-middleware/client', from entry in webpack, however I am still seeing requests on server. Not sure why that is.

-- update -- it was a cache problem.

removing `'webpack-hot-middleware/client' fixed problem.

Thanks!

[jsrraman]

@glenjamin Thanks for the direction. Removing 'webpack-hot-middleware/client' from 'entry' section fixed this.

Just wanted to understand, why this setting was suggested in the 'entry' section of react hot boilerplate?

[glenjamin]

@jsrraman If you add that into the config, it will connect to the server and perform the function this middleware is supposed to do.

If you take it out, it won't do anything. In the comments above people appeared to have disabled or moved the server component, but had left the client in.

[wassubaba]

Hi glenjamin,
I am getting the below exception while trying to connect from web to api.
"Uncaught DOMException: Failed to construct 'EventSource': Cannot open an EventSource to 'http://localhost:8080__webpack_hmr'. The URL is invalid."

Could you please help me to resolve this problem ?

[maciej-gurban]

@wassubaba Late to the party, but in case others stumble upon this, it looks like you forgot a slash after your hostname. The correct HMR URL should be your.domain/__webpack_hmr.

All in all, it would be great to be able to change the __webpack_hmr part into something custom. The use case is running one HMR at localhost, and another at localhost/foo. Without being able to specify a custom URL, it's necessary to do custom URL rewriting rules or use odd hacks to get it working.