Hey martinbigio, thanks for reporting this issue!

React Native, as you've probably heard, is getting really popular and truth is we're getting a bit overwhelmed by the activity surrounding it. There are just too many issues for us to manage properly.

• If you don't know how to do something or something is not working as you expect but not sure it's a bug, please ask on StackOverflow with the tag react-native or for more real time interactions, ask on Discord in the #react-native channel.
• If this is a feature request or a bug that you would like to be fixed, please report it on Product Pains. It has a ranking feature that lets us focus on the most important issues the community is experiencing.
• We welcome clear issues and PRs that are ready for in-depth discussion. Please provide screenshots where appropriate and always mention the version of React Native you're using. Thank you for your contributions!

Using the latest v0.21.0-rc I can't seem to figure out how to enable HMR, should there be a dev menu option?
I simply ran react-native init then npm install --save react-native@0.21.0-rc.

@JohnyDays For now you need to install from master - http://facebook.github.io/react-native/docs/android-setup.html#content

Thanks, I'll give it a look and give some feedback 👍

@JohnyDays 😄

For anyone stuck in making it work, there is no need to install from master, here are the steps for a new project:

1. react-native init ProjectName && cd ProjectName
2. npm install --save react-native@0.21.0-rc
3. react-native upgrade (Choose yes for everything it asks)
4. You're done! An option to enable hot reload should appear in the android dev menu

Oh! I thought @martinbigio removed it before the RC. Finally we have HMR for Android in a public release 🎉

It seems to work perfectly, but everytime a change happens, this warning pops up

And it keeps stacking up at the bottom of the app, so if I save the file 5 times, it appears 5 times (consistently)

EDIT: Actual chrome stacktrace:

Possible Unhandled Promise Rejection (id: 0):
Network request failed
TypeError: Network request failed
    at xhr.onload (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:5883:8)
    at XMLHttpRequest._sendLoad (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:19736:1)
    at XMLHttpRequest.setReadyState (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:19726:6)
    at XMLHttpRequest._didCompleteResponse (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:19621:6)
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:19575:105
    at EventEmitter.emit (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:17889:23)
    at MessageQueue.__callFunction (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:16519:23)
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:16423:8
    at guard (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:16377:1)
    at MessageQueue.callFunctionReturnFlushedQueue (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true:16422:1)

Figured out the problem.
The source maps are being requested from :

http://localhost:8081/index.android.map?platform=android&runModule=false&entryModuleOnly=true&hot=true

It should probably be requested from the remote url/ip (e.g 192.168.1.183).
Is this packager related, or android-specific?
At the end of the generated HMR patch, the sourcemaps are referenced as

//# sourceMappingURL=/index.android.map?platform=android&dev=true&hot=true

UPDATE: If debugging in chrome, changing the url from localhost:8081 to $YOUR_IP:8081 will stop this warning. But I haven't found a way to do this if you're not debugging on chrome Nevermind, doesn't look like it worked very well

Hmm though @mkonicek removed it. It wasn't intended to have the option visible on the menu yet

Ohh, this is 0.21RC. We'll remove the option from the menu there. If everything goes well we should be able to open the feature on 0.22 :)

@JohnyDays Thanks so much for working on adding support for having multiple clients!. Please let us know if you find any bug or if there're other feature requests you think we should implement. We'll need help on testing this, so the more people use it before it's open the better :)

I'm having some trouble getting the android version to compile my java code changes.

I have react-native cloned into the node_modules folder, and when I run react-native run-android it doesn't seem to pick up on them, regardless of me changing branches or whatever I do.
I tried doing cd android && ./gradlew clean but had the same result. Is there something obvious I'm missing?

As an aside, symlinking react-native from another folder makes it so the packager doesn't correctly serve the files

@JohnyDays follow the instructions here - http://facebook.github.io/react-native/docs/android-setup.html#content

Symlinking won't work, coz watchman, which RN uses to watch files, doesn't support symlinks.

Yeah I have my machine (arch-linux) setup with the sdk, and gradle daemon, all the build tools and genymotion.
The builds always succeed, my problem seems to be related to the file system changes not being picked up.
I started a new project and it works perfectly again, it's probably a linux-interop problem.

Shaping up! Still get those warnings though 😢

PS: I just spent way more time than I should trying to make that gif under 10mb, sorry for the terrible colors

@martinbigio Just a heads up, i reimplemented the changes to attachHMRServer.js from b2b41da and 20588a6, so there wouldn't be any problems with conflicts. I should be able to open the PR today, cheers 🍺

Wow, this indeed will be helpful for a lot of people!.

I recently added support for redux stores and modules that export pure functions and modified this file (436db67). Most likely you'll have to rebase.

Just updated to rn-0.22 and the warnings(as shown by @JohnyDays) are still there

Yep, I am also getting this on genymotion with react-native 0.22. I also tried setting debug server host & port to point to my development machine, no luck.

EDIT: When I edit and save a file on the editor I see 'Hot Loading...' toast on genymotion. I guess application is aware of the change but fails to load.

@martinbigio I did some digging on this when i was working on multiple clients, and it appears to be related to source maps. e.g even if you are requesting from a remote ip, the source maps still point to localhost.

Genymotion sets a special ip to access localhost from the simulator, however to fetch the sourcemaps we're using localhost...

The problem is that JS lacks of this logic:

cc @mkonicek

Shouldn't it be the java sending this information to the packager? Such as genymotion=true or localhost=10.0.3.2 in the url

Yup, we're going to expose this on the AndroidConstants native module. @satya164 will send a PR in a couple of hours :)

same error as above still

react-native version:
➜ AwesomeReactNative git:(master) ✗ react-native -v
react-native-cli: 0.2.0
react-native: 0.22.2