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Could you please expand the current answers to some the questions and fill in the currently blank answers? For example, it would probably help a lot to know what you've done exactly when trying to renew instead of just "used acme-v2 api".. How did you use it? Which client? Also, regarding the output there's usually a lot more output in stead of just the error presented by the ACME server.
When this string is returned from the Let's Encrypt ACME CA server software (Boulder), it indicates that the ACME client software you are using has sent a message to the server containing incorrectly structured information per the ACME standard. As @Osiris indicated, without further information we are unable to provide further help.
