Our client cert expired and when I created a new client signer cert to import into the gateway to follow error occurs.
Release : 10.x
Normally this is caused by the import cannot extract the public key from the certificte file.
Certain java versions contain bug for the interop issue:
Make sure it uses the compatible Java version tool to generate the private key, it is better to use the policy manager to create the private key and export and then import to other gateway.