Sometimes you open your app — in the preview panel inside Caffeine, or at its live URL — and all you see is a blank white screen. Nothing loads. This almost always means the app started to load but hit an error in the browser that stopped it before anything could appear. The good news: your browser quietly records exactly what went wrong, and once you share that record with the AI, it can usually pinpoint and fix the cause in the next build.
What a blank screen means
A white or blank screen is different from a deployment that failed or an app that is still starting up. The page itself loaded, but something in your app's frontend code threw an error during startup, so the screen was never drawn.
Caffeine cannot see this error on its own. The error happens inside your browser, on your device, while your app runs — Caffeine does not have access to your running app or to your browser. That is why, when you ask for help with a blank screen, the AI will ask you to collect the error from your browser and paste it into the chat. With that text, the AI can read the exact failure and fix it. Without it, the AI is guessing.
Before collecting errors, rule out the quick causes:
- Give it a moment. A newly built draft or a freshly deployed live version can take 30–60 seconds to become reachable. Wait, then reload.
- Confirm you are looking at the right version. The draft preview can behave differently from the live app. If the live URL is blank, note whether the draft preview works, and vice versa.
- Try a clean browser session. Open the app in a private/incognito window, or a different browser. Browser extensions and cached data can interfere with loading. If it works in a clean session, the problem is local to your browser, not your app.
If the screen is still blank after that, collect the error and share it with the AI.
How to collect the error and share it with the AI
Your browser keeps a log of errors in a tool called the developer console. Opening it and copying the red error messages is the single most useful thing you can do — it turns "it's just blank" into something the AI can act on.
1. Open the page that is blank
Open the app where you see the blank screen. If it is your live app, open the live URL in its own browser tab. If it is the draft preview, you can open the developer console directly on the Caffeine page — it captures the preview's errors too.
2. Open the developer console
- Chrome, Edge, or Brave: right-click anywhere on the page, choose Inspect, then click the Console tab. (Shortcut:
F12on Windows, orCmd+Option+Jon Mac.) - Firefox: right-click anywhere on the page, choose Inspect, then click the Console tab. (Shortcut:
F12on Windows, orCmd+Option+Kon Mac.) - Safari: first turn on developer tools — go to Safari → Settings → Advanced and tick Show features for web developers. Then choose Develop → Show JavaScript Console (shortcut
Cmd+Option+C).
3. Reload the page with the console open
Errors are usually thrown the moment the app starts. Reload the page while the console is open so it captures everything from the beginning.
4. Copy the errors
Look for lines shown in red — these are the errors. Select the error text (including any indented detail underneath it, often called the "stack trace"), then copy it. Many browsers also let you right-click an error and choose Copy or Copy message. If there are several red lines, copy them all.
A screenshot of the console helps too, but pasting the actual text is best — the AI can read every detail and the exact line that failed.
5. Paste it into the Caffeine chat
Go back to your project chat and paste the errors, with a short note about what you were doing. For example:
My app shows a blank white screen when it opens. Here are the errors from the browser console: [paste]
The AI reads the error, identifies the part of your app's code responsible, and fixes it in the next build. If the error mentions a failed network request, also open the Network tab in the same developer tools, reload, and tell the AI which request shows a red or failed status — that points to a backend call that did not complete.
If you cannot open the console
If you are on a phone or cannot access developer tools, you can still help the AI:
- Describe exactly what you see (fully blank, a flash of content that then disappears, a spinner that never finishes).
- Note when it started — for example, "it worked before my last build" or "it has never loaded since I added the login screen."
- Try the same app on a desktop browser where the console is available, and collect the error there.
Then describe this to the AI in the chat. The more precise you are about when the blank screen appears, the faster the AI can narrow it down.
Frequently asked questions
Why does the AI need me to copy the error? Can't it just see it?
No. The error happens inside your browser while your app runs on your device. Caffeine builds and deploys your app, but it does not have access to your running app or your browser session, so it cannot read the error on its own. Copying the console text is what gives the AI the exact failure to fix.
My draft preview is blank but the build said it succeeded. Is that a contradiction?
Not necessarily. A build can compile and deploy successfully and still hit an error when the app actually runs in the browser — for example, a value that is missing at startup. The build check confirms the code compiled; the console error explains what went wrong when it ran. Collect the console error and paste it into the chat so the AI can fix the runtime problem.
The console shows a lot of messages. Which ones matter?
Focus on lines shown in red — those are errors. Yellow lines are warnings and are usually less important. If you are unsure, copy everything red and paste it in; the AI will identify what is relevant.
I see an error like IC0508 or "Service temporarily unavailable."
That is not a code error — it usually means a canister briefly ran low on resources. Caffeine tops these up automatically. Wait and reload your app. See Understanding Canister Cycles for details. If a blank screen persists after the app is reachable again, collect the console error as described above.
Pasting the error didn't fix it. What now?
Reload with the console open and check whether the error changed after the latest build. Paste the new error in — sometimes one fix reveals a second issue underneath. Keep sharing each error you see; the AI works through them one at a time until the app loads.