Symptoms

When you try to execute the application, the following error appears:

Execution failed for task ':processDebugManifest'.
> Manifest merger failed : uses-sdk:minSdkVersion 19 cannot be smaller than version 21 declared in library [:abbyy-rtr-sdk-1.0:] C:\Users\INNOVACION TECNOLOGI\.gradle\caches\transforms-1\files-1.1\abbyy-rtr-sdk-1.0.aar\69ea19ffd3f0e4d862b268028033a46f\AndroidManifest.xml as the library might be using APIs not available in 19

Cause

The issue in the compatible library with a minSdk.

Resolution

In this situation will be better to use 19 version but you can also add in the build Gradle the following:

android 
{
compileSdkVersion 21
 defaultConfig 
{ 
 minSdkVersion 19 or above here
 } 
}