Found 2 records.

Status: Reported (2)

RFC 8617, "The Authenticated Received Chain (ARC) Protocol", July 2019

Errata ID: 7910
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Steffen Nurpmeso
Date Reported: 2024-04-26

Section 4.1.2 says:

   arc-ams-info = instance [CFWS] ";" tag-list
   arc-message-signature = "ARC-Message-Signature:" [CFWS] arc-ams-info

It should say:

   arc-ams-info = instance [FWS] ";" tag-list
   arc-message-signature = "ARC-Message-Signature:" [FWS] arc-ams-info

Notes:

The RFC claims in 4.1.2

The AMS header field has the same syntax and semantics as the DKIM-
Signature field [RFC6376], with three (3) differences:

but the three differences do not denote the FWS->CFWS change.

CFWS is to be parsed very differently than FWS, given its potentially infinite recursion behaviour, and the possibility to use quoted-pair's, ie, "escapability", something which (like almost RFC 5322 as such in practice) the DKIM RFC circumvents by using VALCHAR, a corruption of VCHAR as of RFC 5234.
In effect neither of these standards adhere to neither of RFC 5322 (plain atext, quoted-string, quoted-pair) nor RFC 2045 (K=V without whitespace; quoted-printable or base64 for 7-bit clarity etc etc), making them very hard to parse, to mention my humble opinion.

Errata ID: 8357
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Robert Sayre
Date Reported: 2025-03-30

Section 5.2.2 says:

5.2.2.  Responding to ARC Validation Failures during the SMTP
        Transaction

   If an ARC Validator determines that the incoming message fails ARC
   validation, the Validator MAY signal the breakage through the
   extended SMTP response code 5.7.29 ("ARC validation failure") and the
   corresponding SMTP basic response code.

It should say:

The text is fine, but an SMTP RFC is not cited.

Notes:

Cite RFC 5321 or a replacement.

Report New Errata