Android Studio: Unable to obtain result of 'adb version'

Found the solution thanks to @user3109468, Android Studio had the directory for the Android SDK wrong. In File>Project Structure make sure the directory for the SDK is correct; mine was C:\Users\[user]\AppData\Local\Android\sdk (Google had given sdk a capital "S" for some reason...)

Uncheck: enable adb integration from Tools>Android and re-enable it.

This worked for me.