Invalid XML character
XML 1.0 forbids most control characters, even when written as numeric references. Identify the original character in the source. Escape markup characters with the proper entity; escaping does not make a forbidden code point legal.
Replace or correctly encode forbidden characters
XML 1.0 forbids most control characters, even when written as numeric references. Identify the original character in the source. Escape markup characters with the proper entity; escaping does not make a forbidden code point legal.
Reproduced engine diagnostics and complete fixes
Original minimal examples checked on 2 November 2026. Engine wording differs; follow the cause, not a message alone.
libxml2-wasm 0.7.2
PCDATA invalid Char value 1Xerces2-J 2.12.2 / Temurin Java 21.0.13+9-LTS
An invalid XML character (Unicode: 0x1) was found in the element content of the document.lxml 6.0.2 / libxml2 2.14.6
PCDATA invalid Char value 1.NET 10.0.14 / System.Xml
'', hexadecimal value 0x01, is an invalid character. Line 1, position 4.Repeat this check in your workflow
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