xerces-c version has been pushed to 3.2.0, and old 3.1.4 .tar.gz package is not available on any mirrors.
confirmed: GENTOO_MIRRORS="" ebuild xerces-c-3.1.4-r1.ebuild fetch [...] 2017-12-19 03:14:23 ERROR 404: Not Found. !!! Couldn't download 'xerces-c-3.1.4.tar.gz'. Aborting. You should be able to install, if you setup the gentoo mirrors.
commit 16bbb4ba9ade8f130bfb7039ba7512a79f7f0a2e Author: Sam James <sam@gentoo.org> Date: Mon Apr 21 12:44:10 2025 +0100 dev-libs/xerces-c: add fallback SRC_URI Per https://dlcdn.apache.org/ > The directories linked below contain current software releases from the > Apache Software Foundation projects. Older non-recommended releases can > be found on our archive site. Closes: https://bugs.gentoo.org/946318 Signed-off-by: Sam James <sam@gentoo.org>