When defining the path to the keystore.properties file, keep this fact in mind. When building android/app/build.gradle will search for keystore.properties file not by the relative path of the project, but by the relative path of the android folder. For example, if you put keystore.properties in the android folder and specify the path of def keystorePropertiesFile = rootProject.file('android/keystore.properties') then it will be an error. The file will not be found. With this arrangement, the correct path will be
def keystorePropertiesFile = rootProject.file('keystore.properties') Good luck!