withastro/astro · warning

Internal Warning: route cache overwritten. (${key})

Error message

Internal Warning: route cache overwritten. (${key})

What it means

RouteCache stores each route's getStaticPaths() result keyed by route+component and expects set() to run once. In production runtime mode it warns before overwriting an entry that already has staticPaths, because that means getStaticPaths (or route initialization) executed twice — the 'Internal Warning' prefix signals this is an invariant breach, normally triggered by integrations or an Astro bug rather than page code.

Source

Thrown at packages/astro/src/core/render/route-cache.ts:126

	private runtimeMode: RuntimeMode;

	constructor(logger: AstroLogger, runtimeMode: RuntimeMode = 'production') {
		this.logger = logger;
		this.runtimeMode = runtimeMode;
	}

	/** Clear the cache. */
	clearAll() {
		this.cache = {};
	}

	set(route: RouteData, entry: RouteCacheEntry): void {
		const key = this.key(route);
		// NOTE: This shouldn't be called on an already-cached component.
		// Warn here so that an unexpected double-call of getStaticPaths()
		// isn't invisible and developer can track down the issue.
		if (this.runtimeMode === 'production' && this.cache[key]?.staticPaths) {
			this.logger.warn(null, `Internal Warning: route cache overwritten. (${key})`);
		}
		this.cache[key] = entry;
	}

	get(route: RouteData): RouteCacheEntry | undefined {
		return this.cache[this.key(route)];
	}

	key(route: RouteData) {
		return `${route.route}_${route.component}`;
	}
}

const routeCaches = createManifestMemo(
	(manifest) => new RouteCache(getLogger(manifest), getEnvironment(manifest).runtimeMode),
);

/**

View on GitHub (pinned to 52e6c34790)

Solutions

1. Update Astro to the latest patch release in case the invariant breach is already fixed
2. Audit integrations that invoke a second render/build pass and make them reuse one container and route cache
3. If it reproduces with stock configuration, open an astro repo issue with the full build log and a minimal repro

const existing = routeCache.get(route);
if (existing?.staticPaths) {
  // reuse the cached entry; do not call set() again
} else {
  routeCache.set(route, entry);
}

When it happens

Trigger: During a production build or SSR render, RouteCache.set() is called twice for the same route when the first entry already stored staticPaths — e.g. an integration spinning up a second render pipeline over the same manifest, or duplicated build state.

Common situations: Custom integrations that re-render routes or rebuild the app container; tooling that re-runs the render step over built output; rare Astro internal regressions across versions.

Related errors

• PageNumberParamNotFound
• PrerenderDynamicEndpointPathCollide
• Missing parameter: ${part.content}
• GetStaticPathsInvalidRouteParam
• [MDX] A remark or rehype plugin attempted to inject invalid

AI-assisted analysis of withastro/astro@52e6c34790 (2026-08-18). Data as JSON: /api/errors/23fb5cce6eeb6654. Report an issue: GitHub.