Android Question app bundle

[Never99]

Being a beginner in practice and, returning after a long time on google play console, when a new app is published, and inserting the .aab file, I get this writing.
I searched the forum for answers to this, unfortunately without finding the solution.
Can any good soul help me step by step to solve this issue for publication and explain me? A thousand thanks.

translate in red "the app bundle was not signed".

 

[Shelby]

Try putting in the search field above:
"the app bundle was not signed"