# EPUBCheck RSC-010: Reference to non-standard resource type…

Source: https://epublab.com/epubcheck/rsc-010/ (updated 2026-11-03)

EPUBCheck RSC-010 is an error message: “Reference to non-standard resource type found.” A hyperlink points to a file that is not a document a reading app can display, such as a plain image or another non-content file inside the EPUB.

- Official message (EPUBCheck 5.4.0): Reference to non-standard resource type found.
- Default severity: Error

## Typical causes

- A link to an image file instead of to the page that shows it.
- A link to an embedded file such as a PDF or text file.

## How to fix it

- Point the link at an XHTML document that contains the image or content.
- Or remove the link if readers cannot open the target anyway.

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