The specified Android SDK Build

The specified Android SDK Build Tools version (26.0.2) is   
ignored, as it is below the minimum supported version (27.0.3) 
for Android Gradle Plugin 3.1.2.
Android SDK Build Tools 27.0.3 will be used.
To suppress this warning, remove "buildToolsVersion '26.0.2'" 
from    your build.gradle file, as each version of the Android 
Gradle Plugin    now has a default version of the build tools.
Update Build Tools version and sync project
 Open File


Configuration 'compile' is obsolete and has been replaced with 
'implementation' and 'api'.
It will be removed at the end of 2018. For more information see: 
http://d.android.com/r/tools/update-dependency-configurations.html

如果你出现这个错误，且你已经在你的APP里面修改你build.gradle文件，但还是出错，这个时候你就要注意了，可能是你所依赖的项目里面还有没有更改的。

所以，你只要看下你依赖的包里面有没有还未更改的build.gradle，你把它改过来就可以了。