# Common RN errors and fixes

## NPM Clean Script:
```bash
rm -rf node_modules/ && rm -rf /tmp/metro-bundler-cache-* && watchman watch-del-all
```

## Issue: Android: Unable to load script from assets 'index.android.bundle'
```bash
react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res
```

## Issue: iOS Simulator not opening properly:
```bash
 rm -rf /tmp/metro-bundler-cache-* && watchman watch-del-all
```

## Error:: typeError: undefined is not an object (evaluating '_this._setComponentRef.bind')
- Fix: check bable.config.js, && add module: '@babel/plugin-transform-flow-strip-types'
Also run:
```bash
react-native start --reset-cache
```
## Unresolved Android Dependencies
- Fix: Update the build.gradle file in android/app/
```java
android {
    compileSdkVersion 27
    buildToolsVersion '27.0.3'

    defaultConfig {
        applicationId "com.micropayments"
        missingDimensionStrategy "RNN.reactNativeVersion", "reactNative55_4"
        minSdkVersion 18
        targetSdkVersion 25
        versionCode 101
        versionName "2.0"
        multiDexEnabled true
        ndk {
            abiFilters "armeabi-v7a", "x86"
        }
        manifestPlaceholders = [
            FABRIC_API_KEY: project.env.get("FABRIC_API_KEY"),
            FABRIC_SECRET: project.env.get("FABRIC_SECRET")
        ]
    }...
```

## 'config.h' solution:
```bash
cd ./node_modules/react-native && scripts/ios-install-third-party.sh && cd third-party && cd $(ls | grep 'glog' | awk '{print $1}') && ./configure
```


## Fixing Xcode:
Potential Fix
*Note: If using an old version of React-Native but a new version of Xcode, you need to disable the new build system in favor of the legacy one.  Follow these steps:
 -In Xcode, Select File -> Project/Workspace Setting. You will see a Build System option to select the Legacy Build System as shown below

## Overview

Sometimes Xcode can get in an odd state. This guide is a progression of steps to reset things. After each step, test to see the problem is resolved.

### Clean the Build

If the issue is building, the first step is to clean the build, which will force a clean build from scratch. Choose *Product*, and *Clean*.

### Reset the Simulator

Launch the iOS Simulator. From the *iOS Simulator* menu, choose *Reset Content and Settings...*, and click *Reset* to confirm.

### Delete Derived Data

Choose *Window* -> *Organizer*. Select the *Projects* tab. Select your project on the left. Next to the *Derived Data* line, there click the *Delete* button.

When Xcode creates Derived Data when it index your files, among other things.

It can also be deleted manually at the following path: /Users/{UserName}/Library/Developer/Xcode/DerivedData

### Delete the Module Cache

Within the same folder as your project's Derived Data is a Module Cache. When Code Completion stopped working, deleting this fixed it.

Close Xcode and delete the `~/Library/Developer/Xcode/DerivedData/ModuleCache` directory.

### Delete Xcode Preferences

A long-shot next step is to reset Xcode's preferences. In your terminal, run:

```
defaults delete com.apple.dt.Xcode
```