Short answer
Open the published site, open your browser’s developer tools, and read the first red error in the console. It points to the cause. Lovable’s debugging guide suggests pasting that exact error into the project chat. If the console is clean, check that you published your latest changes and that you’re on the right address.
The causes, from Lovable’s docs
01
Your latest changes aren’t published
“later changes are not automatically pushed live” Lovable, Publish your Lovable project
The live site is a snapshot of your last publish. Open Publish, click Publish changes, and wait for "Your website is live". Also check you’re on the right address: by default the lovable.app link uses your project’s URL subdomain, which can differ from the project’s name.
02
An error stops the app from drawing
“A blank preview usually comes from an error in the app itself.” Lovable, Preview and test your app
Lovable’s docs say a blank preview usually comes from an error in the app itself, and its debugging guide uses a blank published site as its example. The console error names the file. Paste it into the Lovable chat.
03
Your custom domain isn’t serving the app
“These errors come from Cloudflare's proxy, not from Lovable.” Lovable, Set up a custom domain
If the lovable.app address works but your own domain doesn’t, it’s the domain. Remove any AAAA records for it, since Lovable’s docs say they can route traffic incorrectly, and allow time for DNS changes to spread. For Cloudflare error 1001 or 1003, set the Lovable records to DNS only instead of Proxied.
04
Hosted outside Lovable without the build values
“browser values are embedded at build time.” Lovable, Deploying and hosting outside Lovable
If you deploy the code to Netlify, Vercel or your own server, set VITE_SUPABASE_URL and VITE_SUPABASE_PUBLISHABLE_KEY on the host before it builds; without them the app can fail to start. Setting them afterwards doesn’t help until you rebuild.
05
A Lovable incident
Sometimes it isn’t your app. On March 27, 2026, Lovable’s status page reported published projects showing blank pages, said republishing should fix it, and marked it resolved the same day. If a page goes blank without a change on your side, check status.lovable.dev, then republish.
Checked against the vendor’s docs on : Lovable docs: Publish your Lovable project; Lovable docs: Preview and test your app; Lovable docs: Debug and improve your app; Lovable docs: Set up a custom domain; Lovable docs: Deploying and hosting outside Lovable; Lovable status: published projects displaying blank pages (March 27, 2026).
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Related: Bolt or Lovable build fails on deploy · Lovable app rescue: 7 problems to check