I got the above error compileSdk() not found. While creating the app I have installed TargetSdk 31 and min SDK 19 But Apk does not install on Oreo Version so I have changed TargetSdk 31 to 31 and minSdk 19 to 16. I have uninstalled SDK 31 but it partially uninstalls. Please help me to solve this problem I am new to Android.