[API]Circular references in templates causes "RangeError: Maximum call stack size exceeded" error

Author: broofaCreated Feb 21, 2026Updated Feb 21, 2026

Description

If two templates reference one another, nunjucks.render() fails with the following error:

bash

/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/lib.js:32
    err = new Error(old.message);
          ^

Template render error: (/private/tmp/nunjucks_circular_dependency_test/a.njk)
Template render error: (/private/tmp/nunjucks_circular_dependency_test/a.njk)
Template render error: (/private/tmp/nunjucks_circular_dependency_test/a.njk)
...
...line repeats ~1,500 times
...
  RangeError: Maximum call stack size exceeded
    at Object._prettifyError (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/lib.js:32:11)
    at /private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:464:19
    at Template.root [as rootRenderFunc] (eval at _compile (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:527:18), <anonymous>:23:3)
    at Template.render (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:454:10)
    at /private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:301:27
    at createTemplate (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:254:9)
    at handle (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:265:11)
    at /private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/environment.js:276:9
    at next (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/lib.js:258:7)
    at Object.asyncIter (/private/tmp/nunjucks_circular_dependency_test/node_modules/nunjucks/src/lib.js:263:3)

Node.js v24.2.0

How to reproduce

Unzip the following [small, minimal] project nunjucks_circular_dependency_test.zip
cd nunjucks_circular_dependency_test
npm install
npm test

Expected behavior

The Error#message should be concise and descriptive (i.e. not 1,500 lines long!)
It should describe the problem (circular dependency between templates). Ideally it would describe all of the templates involed in the dependency. (e.g. "Circular dependency detected: a.njk -> b.njk -> a.njk".
It should contain appropriate lineno and colno properties.

Source: mozilla/nunjucks

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