The Play Store error probably indicated that your application should support API 26, which means that your compileSdkVersion
and targetSdkVersion
must have a value of 26 or more. In practice, the first attribute indicates which features it can use, so that you get build errors when trying, for example, to use an unsupported method; and the second is an indication that the application supports the informed version. This reply (in English) has more information.
Having this clarified, my suggestion is to update Android Studio to a version higher than 3.0; and update the compileSdkVersion
and targetSdkVersion
from the app to the latest possible versions (>=26) and sync Gradle. During the change of versions you will probably have to update other dependencies, such as Gradle Build Tools and other libraries. A tip is to keep the dependencies of Android Support in its version 27, because in the next version are introduced changes related to Androidx that you probably do not want to use (it is necessary to convert the application as all visual support components are moved to other packages).