I want to update the apk I uploaded previously in alpha and when I wanted to upload it, this error appears, could someone guide me in what I should do? please and thank you very much for your help
If you are going to upload a .apk to Google Play it is strictly necessary that the .apk to upload be signed with the same keystore with which the current application is found, this still applies to Alpha and Beta testing.
This keystore that you generated to sign your application is extremely important to save it, make backup and avoid losing it! because you will not be able to upload signed updates of your application in case of losing it. If you lose it you will be forced to create a new signature and upload another different application.
Review this answer: