CharRef: invalid hexadecimal value

What it means

After &#x, XML accepts only hexadecimal digits 0–9, A–F and a–f until the required semicolon. Any other character means the parser cannot turn the reference into a Unicode code point.

The message is about syntax before it is about the resulting character. First make the digits valid; a separate invalid-character message may still follow if the resulting code point is forbidden in XML.

What usually causes it

• A reference copied with the literal placeholder &#xZZ; or &#xNN; still in it.
• A decimal value written after the x even though it contains digits outside hexadecimal notation.
• A truncated or templated value that inserted punctuation before the closing semicolon.
• Confusing a Unicode name such as U+00A9 with the digits a character reference expects.

How to fix it

• Use only hexadecimal digits and close the reference with a semicolon: © for ©.
• Remove the x when the number is decimal: © is the same character.
• Prefer writing the Unicode character directly in a UTF-8 document when a reference adds no clarity.

The same error elsewhere

Different parsers, same defect. If you arrived with one of these messages, you are in the right place.

• expat (Python)

  not well-formed (invalid token): line 1, column 9

• Xerces (Java)

  A hexadecimal representation must immediately follow the &#x in a character reference.