Failed to resolve: com.android.support:appcompat-v7:15.+

After you downloaded the latest support library with your sdk manager, you can set that version in your gradle file.

If you downloaded 23.0.1 set it like this:

compile 'com.android.support:appcompat-v7:23.0.1'

EDIT: Also note following hint, given by Android Studio, when using + in Version number:

Avoid using + in version numbers; can lead to unpredictable and unrepeatable builds (com.android.support:appcompat-v7:23.1.+)

Using + in dependencies lets you automatically pick up the latest available version rather than a specific, named version. However, this is not recommended; your builds are not repeatable; you may have tested with a slightly different version than what the build server used. (Using a dynamic version as the major version number is more problematic than using it in the minor version position.)

Edit build.gradle

Replace 'com.android.support:appcompat-v7:15.+' with 'com.android.support:appcompat-v7:18.0.0'

Sync It

May be this will help you. If in case this will not work i.e. show error then see for installation of app-compat in "%homepath%\AppData\Local\Android\sdk\extras\android\m2repository\com\android\support\appcompat-v7"

Search for the oldest version and put the version number at xx: 'com.android.support:appcompat-v7:xx'

I installed Java and Android Studio today.

When creating my first project with API level 15 as minSDK, I faced the same problem.

As far as I can tell, it seems the installation of the sdk works not pretty well. For me, API level 15 had only the SDK platform. API level 23 had platform and sources. I don't remember, which tools where installed.

To solve the problem, I started the sdk manager (old version), removed api level 15 completely and installed api level 23 as suggested. After that, a newly created project (again with minSDK 15) was properly created.

The difference in the app/build.gradle file is obvious.

Maybe this helps other people facing the same issues, or one of the gurus can further explain, what happened.

Kind Regards