The document provided by the application claim of oppo App Store is written as follows:

The command format of jarsigner tool signature apk is as follows:

Jarsigner-verbose-keystore[ your signature storage path ]-signed jar[ signed file name] [unsigned file name] [your certificate name]

Here is an example.

Enter the signature command, and then press Enter. For example:

jarsigner-verbose-keystore Android . keystore-signed jar OppoSignVerify _ signed . apk OppoSignVerify . apk Android . keystore

Actually, according to this, this error will be reported.

Jarsigner: The certificate chain for the application could not be found. App must reference a valid keystore key entry that contains a private key and a corresponding public key certificate chain.