[android] Manifest Merger failed with multiple errors in Android Studio

In addition to available solutions, please check this also.
If you have set android:allowBackup="false" in your AndroidManifest.xml then there may be a conflict for android:allowBackup="true" in other dependencies.

Solution
As suggested by @CLIFFORD P Y, switch to Merged Manifest in your AndroidManifest.xml. Android Studio will suggest to add tools:replace="android:allowBackup" in <application /> in your AndroidManifest.xml.