In Android Studio 2.1 I was using API 24 just fine, then suddenly started seeing "Sources for Android API 24 Platform not found" warning in my AndroidManifest.xml.
Rerunning the Android SDK Manager setup in Android Studio, removing other non-supported APIs, etc didn't work for me. How do I fix this?
Try this method , I copied it from here.
Android Studio 2.1 reporting in: solved the issue by resetting SDK.
Preferences -> Appearance & Behavior -> System Settings -> Android SDK.
Click on Edit to the right of Android SDK location. Next, next, next to complete the wizard and voila!