How to Resolve APK Installation Error: Conflicting Package Signatures

When installing APK, if you encounter the error message: "An existing package by the same name with a conflicting signature is already installed." There are three possible reasons:

There is an APK has been installed, so if you install an APK has same package name and different signature, it will notice to you, and forbid the APK to install.
APK has not be signed.
APK is signed, but the certificate is just the debug key or it can not be authenticated by APP root certificate of terminal.

Solving Steps

To reason 1, please remove the installed old APK, then you can install the new one.
To other reason, please apply certificate from wizarPOS. Please refer to How to apply app certificate
Check your key store

   Use the command: keytool -list -keystore xxxx.jks -v
   If the keystore is correct, it should include the certificate the issued by the terminal owner. The default terminal owner is WizarPOS, so if you applied from WizarPOS, your certificate list should include a certificate which issued by the issuer "Issuer: EMAILADDRESS=support@wizarpos.com, CN=releasetestv1, OU=Testing, O=wizarpos, L=Shanghai, ST=Shanghai, C=CN", the result is like the right picture:

Check the alias name of the private key

   If your key store includes some private keys, please select the right private key with alias name, the private key is that be paired with the applied certificate.

Notice

If you use an IDE tool to sign your app, please don't use the default IDE key store. You must use the key store that you have created and applied certificate.