Asset versioning

When you deploy a new frontend build, users with an open tab still run the old JavaScript. Inertia detects this with an asset version: every page object contains the current version, the client sends it back in the X-Inertia-Version header, and when it no longer matches, the next visit becomes a full page load that picks up the new assets.

Default version

The default version is an MD5 hash of the Vite manifest (@webroot/dist/.vite/manifest.json, or @webroot/dist/manifest.json for older Vite versions, see vite.buildPath). It changes whenever you rebuild the assets. Without a manifest the version is an empty string.

Custom version

Set the version when you use another build tool or deploy assets separately:

// config/web.php
'inertia' => [
    'version' => fn () => md5_file(Yii::getAlias('@webroot/assets/manifest.json')),
],

or at runtime:

Inertia::version('2026.09.17');
Inertia::version(fn () => getenv('ASSET_VERSION'));
Inertia::version(null); // back to the default

Inertia::getVersion() returns the current version as a string.

How mismatches are handled

For an Inertia GET request with an outdated version, the adapter does not run the action. It responds with 409 Conflict, the current URL in X-Inertia-Location and the current version in X-Inertia-Version, and the client performs a full page load of the same URL.

Non-GET requests are never interrupted, so form submissions are not lost; the redirect that follows them triggers the reload.

TIP

A version closure is evaluated for every Inertia request. Keep it cheap and stable — a value that changes between requests causes a full reload on every visit.