When was your last update? Kernel 513 is EOL since September 2021.
Please switch to a supported LTS version first and then we’ll go on with the update.
(It will be using the script from this thread: [HowTo] Work around gpg verification issue on left behind systems)
Edit: Sorry, I didn’t see the Spanish tag.
Utilice el script del hilo anterior. Y actualice su kernel a una versión compatible.