Hey,
at the first my english is not the best.
I want to release my project at google play, but if I build the project, then I get this error.
It looks like you do not have a keystore file yet. For a shipping build (for distribution) you must have a keystore file generated. If not then,
Create a new keystore file from cmd prompt.
keytool -genkey -v -keystore my_keystore_filename.keystore -alias my_alias_name -keyalg RSA -keysize 2048 -validity 10000
Secondly, I moved the Keystore file to /Build/Android
Thirdly, in distribution settings in project settings android section set alias name as in keystore file.
AND LASTLY Make sure in distribution settings under keystore name you add the “.keystore” extension to your keystore file name.
If still, you have confusion follow this,