[Android][Redbox Message] Misleading redbox message when starting app for the first time without packager running.

[qbig]

The first time you run(accidentally) RN app without the packager running, the redbox would show the above message. Only after clicking 'reload' the info below would be shown, which is a lot more helpful?

I am not sure but should we use the second redbox info for both cases ?

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[qbig]

 private void recreateReactContextInBackgroundInner() {
    UiThreadUtil.assertOnUiThread();

    if (mUseDeveloperSupport && mJSMainModuleName != null) {
      if (mDevSupportManager.hasUpToDateJSBundleInCache()) {
        // If there is a up-to-date bundle downloaded from server, always use that
        onJSBundleLoadedFromServer();
      } else if (mJSBundleFile == null) {
        mDevSupportManager.handleReloadJS();
      } else {
        mDevSupportManager.isPackagerRunning(
            new DevServerHelper.PackagerStatusCallback() {
              @Override
              public void onPackagerStatusFetched(final boolean packagerIsRunning) {
                UiThreadUtil.runOnUiThread(
                    new Runnable() {
                      @Override
                      public void run() {
                        if (packagerIsRunning) {
                          mDevSupportManager.handleReloadJS();  
                        } else {
                          recreateReactContextInBackgroundFromBundleFile(); // <-- First time run would end up here
                        }
                      }
                    });
              }
            });
      }
      return;
    }

    recreateReactContextInBackgroundFromBundleFile();
  }

if reload is clicked,

                          mDevSupportManager.handleReloadJS();  

would get executed and show the correct the redbox info.

Seems this is the problem ?

                        if (packagerIsRunning) {
                          mDevSupportManager.handleReloadJS();  
                        } else {
                          recreateReactContextInBackgroundFromBundleFile(); // <-- First time run would end up here
                        }

@mkonicek

[ippa]

Also, why not spell it out to new users "Please run 'react-native start' in the root of your project and make sure your device is connected"?

We all know people hate reading long intros ("what is the developmentserver?") and often just starts playing around with new stuff :).

Maybe even mention "adb reverse tcp:8081 tcp:8081" if android is detected.. not sure about this one.

[arypurnomoz]

is there anyway to solve this problem?

[satya164]

PRs are welcome for a better error message.

[qbig]

The root of the issue is that we are calling 'runJSBundle' when there isn't one. And the native cpp implementation throw back the wrong error message. Can fix this in cpp land. But I was struggling getting jni debugging working. Or alternatively, we can check the validity of the bundle before calling 'runJSBundle', which is what I tried in #4738

Any suggestions would be great @satya164 @mkonicek

[mkonicek]

Can we simply replace both error messages with the message iOS has?

IMHO "Can't find variable __fbBatchedBridge" is never useful to anyone. If you can't replace the message in C++, can you detect that exception reliably and throw one with a better message?

The "Unable to download JS bundle" message is not very good either. Replacing that with the clear message should be trivial.

Thanks so much for working on this, the cryptic message has been bothering many people for a long time.

@kmagiera, @foghina What do you think?

[kmagiera]

We used to have a better error message for this case. This looks like a regression then. But yeah, the one on iOS is even better, so let's go with that

[philikon]

As of 0.18.0rc, the __fbBatchedBridge error message is now also the one shown on iOS. Seems like a regression on both platforms.

[mkonicek]

Yeah this is pretty bad. Anyone up for sending a fix?

[satya164]

Not sure if this is the correct way, but here is a PR - #5235