Eleventy "Problem writing Eleventy templates" output in CI

By Kaveh Alemi·Latchkey

Eleventy finished rendering and hit an error while writing the output files. A common trigger is two pages resolving to the same permalink, which Eleventy refuses to overwrite.

What this error means

eleventy build ends with "Problem writing Eleventy templates", sometimes with "Output conflict" naming two input files that map to the same output path.

[11ty] Problem writing Eleventy templates:
[11ty] Output conflict: multiple input files writing to `./_site/about/index.html`.
[11ty]   ./src/about.md and ./src/pages/about.njk

Common causes

Two inputs resolve to the same permalink

Two templates compute the same output path, so the second write would clobber the first; Eleventy treats it as a conflict.

An unwritable or read-only output path

A permalink pointing outside the output directory, or a path the runner cannot write, fails the write step.

How to fix it

Give each page a unique permalink

1. Read the two input files named in the conflict.
2. Change one file's permalink or slug so the outputs differ.
3. Re-run the build to confirm the conflict clears.

---
permalink: /about/team/index.html
---

Keep output paths inside the output dir

Ensure computed permalinks stay under the configured output directory so writes succeed.

export default { dir: { output: '_site' } };

How to prevent it

• Avoid two templates that compute the same permalink.
• Keep permalinks relative and inside the output directory.
• Build locally before pushing to catch output conflicts.

Frequently asked questions

Related guides

References

• Node.js documentation
• npm CLI documentation
• GitHub Actions documentation