A blank page after deploying a JavaScript app is a symptom, not a diagnosis. Start by checking the browser’s first runtime error and failed network requests; then follow the evidence to an asset path, route fallback, runtime configuration, or API issue. The right fix depends on your framework, hosting setup, and the errors you see.
Start with the browser evidence
Open the deployed URL in a browser with developer tools open. Before changing build or hosting settings, record what the browser reports.
- In Console, find the earliest relevant exception. Note its message, filename, and line number if available.
- In Network, reload the page and inspect the document, JavaScript, CSS, code-split chunks, and API requests.
- For each failed request, note its status code, requested path, response content type, and domain. Check whether the URL uses the expected root or subdirectory.
The earliest error or failed request is usually a more useful lead than the blank screen itself. A successful local development run—or even a successful production build—does not establish that the deployed host serves assets and routes correctly.
If JavaScript, chunks, or styles fail to load
Compare the script and stylesheet URLs in the generated HTML with where the app is deployed. A site published under a subdirectory such as /repo/ may fail if its build requests root-relative files such as /assets/app.js instead of files under the deployed base path. A missing asset can also mean the host published the wrong output directory or that the build did not generate the requested file.
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- Check the framework’s configured base path or public path. For Vue CLI, verify the
publicPathsetting; for TanStack Router, follow its production deployment checklist. - Confirm that the hosting service’s output directory matches the directory produced by your build, and that the host serves its static files.
- Where applicable, check that the router’s basename or equivalent matches the deployed subdirectory as well as the asset base path.
Use the actual failed request URL and the files in the deployed output to distinguish a path mismatch from a missing or unpublished file. Do not assume every 404 has the same cause.
If direct routes or refreshes return 404
If in-app navigation works but visiting a client-side route directly—or refreshing it—returns 404, the host may be looking for a physical file at that route instead of returning the app’s entry HTML. For a single-page app that uses browser-history routing, configure the host to serve index.html for valid client routes while still serving real assets and API paths correctly. React Router describes this general SPA requirement in its SPA deployment documentation.
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The configuration is host- and framework-specific. Vercel explains that its routing uses build-generated metadata and documents SPA rewrites in its 404 troubleshooting guide. Vue CLI and Create React App also document history-route fallback behavior in their respective deployment guides: Vue CLI and Create React App. Do not apply a generic catch-all rewrite without checking the app’s routing model; server-rendered and filesystem-routed frameworks may need their own framework-native setup.
If bundles load but the app crashes
When the document and bundles load, use the first Console exception and its stack trace to identify the failing module or initialization step. Then check for differences between the local and deployed runtime, including production build settings, required configuration values, and code that assumes browser APIs are available during server-side or initial rendering.
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For example, React Router notes that browser-only APIs such as window cannot be used during the initial render in SPA mode; Vue’s production guidance covers production setup and runtime-error reporting integrations. See React Router’s SPA guide and Vue’s production deployment guide.
For Vite-based configurations, TanStack’s deployment guidance says exposed environment variables use the VITE_ prefix and that the app should be built with the intended configuration. Treat these as client-side values: anything embedded in browser code is visible to users, so do not put secrets there. If a required value is absent or wrong, correct the deployment configuration and rebuild as needed.
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If the app shell loads but data is missing
Inspect API requests in Network and check their destination, status, and response. Verify that the deployed frontend is using the intended API origin and authentication or configuration settings. If the frontend and backend are hosted on separate origins, the backend may need to allow requests from the deployed frontend through its CORS configuration; Vue CLI calls out this deployment case in its deployment documentation.
A failed API request explains a blank screen only if the app’s rendering depends on that request and handles the failure by leaving the page empty. Otherwise, it may explain missing data while a separate runtime or rendering issue causes the blank page.
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Compare a production build locally with the deployment
Serve the generated build over HTTP rather than opening its HTML file directly. Vue CLI documents serve -s dist as a local SPA preview and notes that opening dist/index.html through file:// is not a valid preview for the usual build setup. See Vue CLI’s local preview instructions.
- If the same failure appears in the HTTP preview, investigate the generated build, application code, and configuration used to build it.
- If the preview works but the deployed site fails, compare the host’s output directory, static-file serving, base path, route fallback, and frontend/API domains.
This comparison narrows the problem; it does not by itself identify which deployment setting is wrong.
Choose the fix for your hosting and routing model
There is no single hosting fix that fits every JavaScript app. Before changing provider settings, establish how the app is rendered and routed, where its build output is published, and whether its API is on another origin.
- Rendering and routing: Is it a static SPA, a server-rendered app, or a framework using filesystem routes?
- Build and assets: Does the host publish the expected output directory and serve assets from the configured root or subdirectory?
- Direct routes: How does this host handle direct client-route requests and refreshes, and can a fallback avoid swallowing asset and API paths?
- API access: Does the deployed frontend need cross-origin access, and can the backend allow the intended origin safely?
Use documentation for the exact framework and hosting combination. Vercel’s rewrite guidance applies to Vercel routing, while React Router, Vue CLI, and Create React App describe their own deployment behavior; their examples are not interchangeable.
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