avajs/ava · error · Error

This version of AVA ( ) does not support any of the desired…

Error message

This version of AVA (${pkg.version}) does not support any of the desired shared worker protocols: ${supportedProtocols.join(',')}

What it means

registerSharedWorker negotiates a protocol between the test file and the shared worker. This AVA version only implements the 'ava-4' protocol (lib/worker/plugin.js:98-100); if the caller's supportedProtocols array does not include 'ava-4', AVA throws this Error listing the protocols the caller offered. It means the shared worker (or the plugin wrapper around it) was written for an incompatible AVA protocol generation.

Solutions

1. Add 'ava-4' to the supportedProtocols array passed to t.registerSharedWorker().
2. Upgrade the shared worker package to a version compatible with your AVA major version, or align AVA's version with the protocol the worker supports.
3. Check pkg.version of the installed AVA and the documented protocol list; only 'ava-4' is accepted by this build.

Example fix

// before
t.registerSharedWorker({
  filename: new URL('./shared-worker.js', import.meta.url),
  supportedProtocols: ['ava-3'],
});

// after
t.registerSharedWorker({
  filename: new URL('./shared-worker.js', import.meta.url),
  supportedProtocols: ['ava-4'],
});

const SUPPORTED_BY_AVA = ['ava-4'];
if (!supportedProtocols.includes('ava-4')) {
  throw new Error(`Shared worker requires AVA protocol 'ava-4'; offered: ${supportedProtocols.join(',')}`);
}

When it happens

Trigger: Calling t.registerSharedWorker({ supportedProtocols: [...], ... }) where the array contains anything other than 'ava-4' — e.g. ['ava-3'], ['shared-worker-1'], or a custom protocol name — inside a test file.

Common situations: Using a shared worker package built for a different AVA major version, upgrading/downgrading AVA while keeping an old shared worker, hand-writing supportedProtocols with a guessed protocol name, or a library emitting version-specific protocols like ['ava-5'] that this AVA build does not speak.

Related errors

• Shared worker is not yet available
• Shared workers can be used only when worker threads are…
• Cannot record snapshot
• Could not compare snapshot
• Did not match snapshot

AI-assisted analysis of avajs/ava@bbfd946322 (2026-09-02). Data as JSON: /api/errors/9d58eb7a34b38918. Report an issue: GitHub.

Appendix: source

Thrown at lib/worker/plugin.js:99

			yield * receiveMessages();
		},
	};
}

export function registerSharedWorker({
	filename,
	initialData,
	supportedProtocols,
	teardown,
}) {
	const options_ = getOptions();

	if (!options_.workerThreads) {
		throw new Error('Shared workers can be used only when worker threads are enabled');
	}

	if (!supportedProtocols.includes('ava-4')) {
		throw new Error(`This version of AVA (${pkg.version}) does not support any of the desired shared worker protocols: ${supportedProtocols.join(',')}`);
	}

	filename = String(filename); // Allow URL instances.

	let worker = workers.get(filename);
	if (worker === undefined) {
		worker = createSharedWorker(filename, initialData, async () => {
			// Run possibly asynchronous teardown functions serially, in reverse
			// order. Any error will crash the worker.
			const teardownFns = workerTeardownFns.get(worker);
			if (teardownFns !== undefined) {
				for await (const fn of [...teardownFns].toReversed()) {
					await fn();
				}
			}
		});
		workers.set(filename, worker);
	}

View on GitHub (pinned to bbfd946322)