Metro Bundler has encountered an internal error, app fails to load

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

Environment: OS: macOS Sierra 10.12.6 Node: 9.4.0 Yarn: 1.3.2 npm: 5.6.0 Watchman: 4.9.0 Xcode: Xcode 9.2 Build version 9C40b Android Studio: 2.3 AI-162.3871768

Packages: (wanted => installed) react: 16.2.0 => 16.2.0 react-native: 0.52.0 => 0.52.0

Steps to Reproduce

1. react-native init AwesomeProject
2. cd AwesomeProject/
3. react-native run-ios

Expected Behavior

App should open without errors in the simulator.

Actual Behavior

2018-01-20 06:56:30.960 [info][tid:main][RCTCxxBridge.mm:210] Initializing <RCTCxxBridge: 0x6040001c9d80> (parent: <RCTBridge: 0x6000000c6740>, executor: (null))
2018-01-20 06:56:30.963580-0800 AwesomeProject[72638:2085234] Initializing <RCTCxxBridge: 0x6040001c9d80> (parent: <RCTBridge: 0x6000000c6740>, executor: (null))
2018-01-20 06:56:31.034 [warn][tid:main][RCTBridge.m:120] Class RCTCxxModule was not exported. Did you forget to use RCT_EXPORT_MODULE()?
2018-01-20 06:56:31.034678-0800 AwesomeProject[72638:2085234] Class RCTCxxModule was not exported. Did you forget to use RCT_EXPORT_MODULE()?
2018-01-20 06:56:31.066 [warn][tid:main][RCTModuleData.mm:69] Module RCTImageLoader requires main queue setup since it overrides `init` but doesn't implement `requiresMainQueueSetup`. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.
2018-01-20 06:56:31.065913-0800 AwesomeProject[72638:2085234] Module RCTImageLoader requires main queue setup since it overrides `init` but doesn't implement `requiresMainQueueSetup`. In a future release React Native will default to initializing all native modules on a background thread unless explicitly opted-out of.
2018-01-20 06:56:31.095 [info][tid:main][RCTRootView.m:302] Running application AwesomeProject ({
    initialProps =     {
    };
    rootTag = 1;
})
2018-01-20 06:56:31.095703-0800 AwesomeProject[72638:2085234] Running application AwesomeProject ({
    initialProps =     {
    };
    rootTag = 1;
})
2018-01-20 06:56:31.250 [error][tid:NSOperationQueue 0x6040000399e0 (QOS: UNSPECIFIED)][RCTCxxBridge.mm:419] Failed to load bundle(http://localhost:8081/index.bundle?platform=ios&dev=true&minify=false) with error:(Metro Bundler has encountered an internal error, please check your terminal error output for more details (null))
2018-01-20 06:56:31.250740-0800 AwesomeProject[72638:2085588] Failed to load bundle(http://localhost:8081/index.bundle?platform=ios&dev=true&minify=false) with error:(Metro Bundler has encountered an internal error, please check your terminal error output for more details (null))

Reproducible Demo

Default app created using react-native init exhibits the issue. I also tried to downgrade to 0.51 but I’m seeing the same issue.

[marlosirapuan]

same here. In my case I solved with this:

kill $(lsof -t -i:8081)

and build again on device

[arapocket]

I have this same issue and I’m on node 8.9.4