# EPUBCheck RSC-024: informative parser warning, how to fix it

Source: https://epubcc.com/epubcheck/rsc-024/ (updated 2026-11-04)

EPUBCheck RSC-024 is a usage message: “Informative parsing warning: ….” The parser reported an informative warning about a file. It is a usage message, shown only with -u, and it does not affect validity; the text after the colon is the parser's own note.

- Official message (EPUBCheck 5.4.0): Informative parsing warning: %1$s
- Default severity: Usage

## Typical causes

- Constructs the parser notices but that break no rule, such as unusual but legal markup.
- Notes from the underlying XML or HTML parser that EPUBCheck passes through.

## How to fix it

1. Read the text after the colon, with the file, line and column.
2. Change the markup only if the note points at something you did not intend.
3. Otherwise ignore it: the EPUB is not invalid because of it.

## When it's not this

A parser warning shown without -u is RSC-017; a real parsing error is RSC-005 or RSC-016.

## Sources

- EPUBCheck 5.4.0 message texts (MessageBundle.properties, w3c/epubcheck on GitHub): https://github.com/w3c/epubcheck/blob/v5.4.0/src/main/resources/com/adobe/epubcheck/messages/MessageBundle.properties (read 2026-11-04)
- EPUBCheck wiki: Running EPUBCheck (command-line options): https://github.com/w3c/epubcheck/wiki/Running (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.