Android dependency 'android.arch.lifecycle:livedata-core' has different version for the compile (1.1.0) and runtime (1.1.1) classpath. You should manually set the same version via DependencyResolution

解决:
Use this code in your buildscript (build.gradle root):

subprojects {
  project.configurations.all {
     resolutionStrategy.eachDependency { details ->
        if (details.requested.group == 'com.android.support'
              && !details.requested.name.contains('multidex') ) {
           details.useVersion "version which should be used - in your case 26.0.0-beta2"
        }
     }
  }
}

并且:

I had the same error, what solve my problem was. In my library instead of using compile or implementation i use "api".

参照