# EPUBCheck CHK-007: Error encountered while processing…

Source: https://epublab.com/epubcheck/chk-007/ (updated 2026-11-03)

EPUBCheck CHK-007 is an error message: “Error encountered while processing custom message file "…": "…".” EPUBCheck failed while processing the custom message file and reports the underlying error.

- Official message (EPUBCheck 5.4.0): Error encountered while processing custom message file "%1$s": "%2$s".
- Default severity: Error

## Typical causes

- A file that is not in the expected tab-separated format, or one that cannot be read.

## How to fix it

- This is a problem with the file passed to EPUBCheck's -c (--customMessages) option, not with the EPUB. Fix the custom message file or run EPUBCheck without -c.
- To start from a correct file, run EPUBCheck with -l (--listChecks) to write the list of message IDs and their severities, then edit that list.

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