Please tell me what is the reason of this Exception
*Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex*
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support:design:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
implementation 'com.android.support:support-vector-drawable:26.1.0'
implementation 'com.google.firebase:firebase-database:11.0.4'
implementation 'com.google.firebase:firebase-storage:11.0.4'
implementation 'com.google.firebase:firebase-auth:11.0.4'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
compile 'io.paperdb:paperdb:2.6'
compile 'com.github.rey5137:material:1.2.4'
compile 'com.theartofdev.edmodo:android-image-cropper:2.6.+'
compile 'de.hdodenhof:circleimageview:2.2.0'