Mobile Development – Common Errors & Fixes

When developing mobile applications for Android or iOS, encountering build errors is a regular part of the process. These errors can stem from SDK misconfigurations, dependency issues, or quirks in cross-platform libraries like React Native. Below is a list of common issues developers face, along with tested solutions.

1. Broken or Missing Build Tools (Android)

Error:

Build-tool 35.0.0 is missing AAPT at /.../build-tools/35.0.0/aapt

FAILURE: Build failed with an exception.
> Installed Build Tools revision 35.0.0 is corrupted. Remove and install again using the SDK Manager.

Symptoms:

• Gradle build fails almost immediately.

• Compilation of Java sources (:app:compileDebugJavaWithJavac) cannot proceed.

• Error points to a corrupted or incomplete installation of Build Tools.

Solution:

1. Open Android Studio.

2. Go to SDK Manager → SDK Tools.

3. Uncheck and re-check Android SDK Build-Tools 35.0.0, then click Apply to reinstall.

4. Alternatively, run:

   sdkmanager --uninstall "build-tools;35.0.0"
   sdkmanager "build-tools;35.0.0"

2. expo run:android Fails – Emulator Not Detected

Error:

adb.exe: device 'emulator-5554' not found
CommandError: Failed to get properties for device (emulator-5554)

Likely Cause:

• The Android Debug Bridge (ADB) cannot find a running emulator.

• Emulator may not be initialized or started properly.

Solution:

1. Start Android Studio.

2. Go to Tools → Device Manager, then launch a virtual device.

3. Verify the emulator is listed using:

   adb devices

   You should see a list like:

   List of devices attached
   emulator-5554   device

Note: If no devices are listed, try restarting ADB:

adb kill-server
adb start-server

3. Path Handling Errors in react-native-libsodium (Windows)

Error Symptoms:

• Build fails due to invalid escape sequences (\A, \b, etc.).

• Common when project paths include backslashes (e.g., D:\Application\...).

Root Cause: CMake interprets \\ in Windows-style paths as escape sequences. This causes malformed paths when building native dependencies.

Solution: Manually modify the CMakeLists.txt file in the react-native-libsodium dependency:

File Path:

node_modules/react-native-libsodium/android/CMakeLists.txt

Fix: Add the following lines to convert NODE_MODULES_DIR into a valid CMake path:

file(TO_CMAKE_PATH "${NODE_MODULES_DIR}" SAFE_NODE_MODULES_DIR)
set(JSI_CPP_PATH "${SAFE_NODE_MODULES_DIR}/react-native/ReactCommon/jsi/jsi/jsi.cpp")

Then replace references to NODE_MODULES_DIR with SAFE_NODE_MODULES_DIR. For example:

# set the base libsodium build directory
set(LIBSODIUM_BUILD_DIR ${CMAKE_CURRENT_LIST_DIR}/../libsodium/build)

# set the libsodium build directory depending on the target abi
if (${ANDROID_ABI} STREQUAL arm64-v8a)
  set(LIBSODIUM_BUILD_DIR ${LIBSODIUM_BUILD_DIR}/libsodium-android-armv8-a+crypto)
elseif(${ANDROID_ABI} STREQUAL armeabi-v7a)
  set(LIBSODIUM_BUILD_DIR ${LIBSODIUM_BUILD_DIR}/libsodium-android-armv7-a)
elseif(${ANDROID_ABI} STREQUAL x86)
  set(LIBSODIUM_BUILD_DIR ${LIBSODIUM_BUILD_DIR}/libsodium-android-i686)
else()
  set(LIBSODIUM_BUILD_DIR ${LIBSODIUM_BUILD_DIR}/libsodium-android-westmere)
endif()

add_library(sodium SHARED IMPORTED)
include_directories( ${LIBSODIUM_BUILD_DIR}/include/ )
set_target_properties( sodium PROPERTIES IMPORTED_LOCATION ${LIBSODIUM_BUILD_DIR}/lib/libsodium.so )

# --- BEGIN MODIFICATION ---
# Convert NODE_MODULES_DIR to a CMake-friendly path
file(TO_CMAKE_PATH "${NODE_MODULES_DIR}" SAFE_NODE_MODULES_DIR)

# Construct the JSI CPP path using the safe path and forward slashes
set(JSI_CPP_PATH "${SAFE_NODE_MODULES_DIR}/react-native/ReactCommon/jsi/jsi/jsi.cpp")

# here we define a library target called "libsodium"
# which will be built from the listed source files
add_library(libsodium
  SHARED
  "${JSI_CPP_PATH}" # Use the corrected path variable
  ../cpp/react-native-libsodium.cpp
  ../cpp/react-native-libsodium.h
  cpp-adapter.cpp
)
# --- END MODIFICATION ---

# link the sodium lib with our "libsodium" library target defined earlier
target_link_libraries(libsodium sodium)

After saving the file: Clean and rebuild your Android project:

cd android
./gradlew clean
cd ..
npx expo run:android

Recommended Tip: Avoid placing your project in folders with capital letters or special characters (e.g., D:\Application\Xion) to reduce CMake path issues.

4. ADB Shows Duplicate or Ghost Devices

Symptoms:

• Android Studio’s AVD only lists one emulator, but adb devices shows multiple.

• Build errors or confusion about which emulator is active.

Cause:

• Stale ADB device entries from previously deleted or corrupted emulator instances.

Fix: Restart the ADB server:

adb kill-server
adb start-server
adb devices

If this doesn't resolve it:

• Delete all unused emulators from Android Studio → Device Manager.

• Recreate new AVDs to avoid misconfigured devices.

Extra Tips for Smooth Builds

• Always use Node.js LTS versions for React Native projects (avoid experimental versions like v23).

• Run npx expo doctor or npx react-native doctor regularly to diagnose config issues.

• Keep your Expo CLI and dependencies up to date:

  npm install -g expo-cli
  npm outdated

Still Stuck?

If you continue to encounter issues:

• Run the command with --verbose or --stacktrace to get detailed logs.