avajs/ava · error · Error

nonSemVerExperiments from ${fileForErrorMessage} must be an

Error message

nonSemVerExperiments from ${fileForErrorMessage} must be an object

What it means

Guard in loadConfig: the merged nonSemVerExperiments value is not a plain object. It must be a map of experiment-name-to-flag values; a string, array, boolean, or null was supplied (directly or via the fileConf/packageConf spread). The input at fault is config.nonSemVerExperiments.

Source

Thrown at lib/load-config.js:168

		if ('ava' in fileConf) {
			throw new Error(`Encountered ’ava’ property in ${fileForErrorMessage}; avoid wrapping the configuration`);
		}
	}

	const config = {
		...defaults, nonSemVerExperiments: {}, ...fileConf, ...packageConf, projectDir, configFile,
	};

	if (
		'filterNodeArgumentsForWorkerThreads' in config
		&& typeof config.filterNodeArgumentsForWorkerThreads !== 'function'
	) {
		throw new Error(`filterNodeArgumentsForWorkerThreads from ${fileForErrorMessage} must be a function`);
	}

	const {nonSemVerExperiments: experiments} = config;
	if (!isPlainObject(experiments)) {
		throw new Error(`nonSemVerExperiments from ${fileForErrorMessage} must be an object`);
	}

	for (const key of Object.keys(experiments)) {
		if (!EXPERIMENTS.has(key)) {
			throw new Error(`nonSemVerExperiments.${key} from ${fileForErrorMessage} is not a supported experiment`);
		}
	}

	return {config, unsupportedFiles};
}

View on GitHub (pinned to bbfd946322)

Solutions

1. Set nonSemVerExperiments to an object literal of experiment flags only
2. Remove the key entirely if not experimenting
3. Fix JSON/JS syntax that accidentally assigns a scalar to the key

When it happens

Trigger: Thrown at lib/load-config.js:168 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of avajs/ava@bbfd946322 (2026-09-02). Data as JSON: /api/errors/e8bb54121c163881. Report an issue: GitHub.