The public key in the specification does not match the vCenter public key. You have to reenter the password in order to proceed.
This issues have been observed since the data-encipherment certificate update.
VMware vCenter Server
Custom specifications created before the renewal of the data-encipherment certificate will fail to decrypt passwords due to the encryption key update.
Edit the customization specification and re-enter the password. This operation allows you to re-encrypt the password.
Japanese KB:仕様内のパブリック キーが vcenter server のパブリック キーと一致しません。