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EPUBCheck · XHTML content documents

HTM-003

Updated:

EPUBCheck HTM-003 is an error message: “External entities are not allowed in EPUB v3 documents. External entity declaration found: ….” An EPUB 3 document declares an external entity, which is not allowed.

The official message

External entities are not allowed in EPUB v3 documents. External entity declaration found: %1$s.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.

Typical causes

  • A DOCTYPE with an internal subset that declares entities from an external file.

How to fix it

  • Remove the entity declarations and write the characters directly or as numeric references.

Terms used here

Other HTM messages

  • HTM-004 Irregular DOCTYPE: found "…", expected "…".
  • HTM-009 The DOCTYPE provided is obsolete or irregular and can be removed.
  • HTM-010 Namespace "…" is unusual for the prefix "epub".
  • HTM-011 Entity is undeclared.
  • HTM-025 Non-registered URI scheme type found in href.
  • HTM-045 Encountered empty href.

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EPUBLab.

FAQ

What does EPUBCheck HTM-003 mean?

EPUBCheck HTM-003 is an error message: “External entities are not allowed in EPUB v3 documents. External entity declaration found: ….” An EPUB 3 document declares an external entity, which is not allowed.

Is HTM-003 an error?

HTM-003 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.