# EPUBCheck RSC-033: query string in a URL, how to fix it

Source: https://epubcc.com/epubcheck/rsc-033/ (updated 2026-11-04)

EPUBCheck RSC-033 is an error message: “Relative URL strings must not have a query component, but found one in "…".” A relative URL contains a query string (?key=value), which EPUB does not allow because there is no server to answer it. The reading app looks for a file whose name includes the query and does not find it.

- Official message (EPUBCheck 5.4.0): Relative URL strings must not have a query component, but found one in "%1$s".
- Default severity: Error

## Typical causes

- Links copied from a website, such as page.xhtml?id=3.
- Cache-busting parameters such as style.css?v=2 added by a build tool.

## How to fix it

1. Find the URL named in the message.
2. Remove the query part from the URL; use a #fragment to point inside a document.
3. If a build step adds it, change the step, then validate again.

## When it's not this

A #fragment on a stylesheet link is only the usage message RSC-013.

## Sources

- EPUB 3.3, §4.2.5 URLs in the OCF abstract container: https://www.w3.org/TR/epub-33/#sec-container-iri (read 2026-11-04)

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