Android Studio 2.2 and 2.3 errors -

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i new android studio user, , have error yet resolve:

error:(26, 13) failed resolve: com.android.support:appcompat-v7:25.0.2

i have updated android studio , support repositories , reinstalled entirely, still not know problem is.

i have attached screenshot of issue. please, how can android studio functional again?

finally resolved it. there hint build file (app) stating there more recent version 'com.android.support:appcompat-v7:25.0.2' , newer version 'com.android.support:appcompat-v7:25.3.1'. changed 25.0.2 25.3.1 in build script manually , synced. cause android studio request download of new support repository. when completes, resolve gradle build issue , issue inability resolve 'appcompatactivity' in .java file.