When I try to upload apk on google play , I receive google play error.
Your APK has been signed with multiple certificates. Please only sign it with one certificate and upload it again.
How to solve that?
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Did you sign your first apk with one key, then signed one of the following apks with another key? The best thing would be to find and use that first key. Otherwise I think you'll need to create a new app ( I may be wrong )