Why do I see decryption failure errors in the serial console?

You see decryption failure errors in the serial console of your IBM Cloud® Hyper Protect Virtual Servers for VPC instance.

The contract isn't encrypted by the correct key.

If you opt to use contract encryption, you must take the correct key. The contract is decrypted by the bootloader and if it's not encrypted by the correct key, you see decryption failures errors in the serial console of the instance.