Eleventy "Template render error" on build in CI

By Kaveh Alemi·Latchkey

Eleventy compiled a template and the engine (Nunjucks, Liquid) threw while rendering it. Eleventy wraps the engine error as "Template render error" and prints the underlying message and the file.

What this error means

eleventy build stops with "Template render error" plus the original engine message, naming the input file and often the line that failed.

[11ty] Problem writing Eleventy templates:
[11ty] Template render error: (./src/post.njk)
[11ty]   Error: Unable to call `title`, which is undefined or falsey

Common causes

A referenced variable is undefined

The template uses data (frontmatter or a global) that is missing for some inputs, so the engine throws when it renders them.

A template syntax error

Malformed tags or an unclosed block in Nunjucks/Liquid make the engine fail at render time.

How to fix it

Guard or default the missing data

Provide a default so the template renders even when the field is absent.

<h1>{{ title or "Untitled" }}</h1>

Fix the template syntax the error names

1. Open the file named in the error at the reported line.
2. Close any unbalanced tags or correct the filter/variable name.
3. Re-run eleventy to confirm the render succeeds.

npx @11ty/eleventy

How to prevent it

• Default optional fields in templates so missing data does not throw.
• Lint templates locally before pushing.
• Keep frontmatter consistent across all content of one type.

Frequently asked questions

Related guides

References

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