Hydration mismatch in production on browserbase/gemini-browser (task finishes without launching browser) #24
Description
Hydration mismatch in production on browserbase/gemini-browser (task finishes without launching browser)
Summary
When running the project in production (VPS with SSL, Nginx reverse proxy), the UI shows "starting gemini" and then "task complete", but no browser session is launched and the automation does not execute. The console displays a React/Next.js hydration mismatch error.
Repository / Version
- Repository: https://github.com/browserbase/gemini-browser
- Branch:
main - Version/commit: (please confirm – I used the latest commit as of Oct 8, 2025)
Environment
- Deploy: Linux VPS with SSL (Let's Encrypt) and Nginx as reverse proxy
- Node.js: v20.x (LTS; I can provide the exact subversion if needed)
- Package manager:
pnpm - Runtime: Next.js (App Router) in production mode (
next build+next start) - Test browsers: Chrome 141, Firefox 131
Relevant environment variables
I followed the README and set, among others:
# Optional: Site URL
NEXT_PUBLIC_SITE_URL=http://localhost:3000Note: In production I'm accessing via a public HTTPS domain behind Nginx.
Others (examples):
BROWSERBASE_API_KEY=***
GEMINI_API_KEY=***
NODE_ENV=productionSteps to reproduce
- Clone the repository and install deps (
pnpm i). - Build for production
pnpm buildand startpnpm start(ornext build/next start). - Publish behind Nginx with SSL (proxy to
localhost:3000). - Open the site and run a prompt in the input field (e.g., "What's the price of NVIDIA stock?" or a navigation instruction).
- The UI shows “starting gemini” and shortly after “task complete”.
- No remote browser is launched, and the automation does not occur.
Expected behavior
- After submitting the prompt, a browser session should be created/launched and the task should run to completion with corresponding logs/result.
Actual behavior
- The UI signals start and immediate completion (without opening a browser).
- A hydration mismatch error appears in the console (and a red popup in the UI).
Error/stack (excerpt)
View message
Error: A tree hydrated but some attributes of the server rendered HTML didn't match the client properties. This won't be patched up.
...
- Possible causes listed by React (SSR/client branch, Date.now/Math.random, locale, external data without snapshot, invalid HTML nesting, browser extension changing DOM before React loads).
...
<html lang="en"
- pwa-launched="true"
- pwa-extension-id="npnbdojkgkbcdfdjlfdmplppdphlhhcf"
- pwa-extension-url-root="chrome-extension://npnbdojkgkbcdfdjlfdmplppdphlhhcf/"
>
...
<form ...
- data-np-autofill-form-type="other"
- data-np-checked="1"
- data-np-watching="1"
>
<input ...
- data-np-intersection-state="visible"
- pwa2-uuid="EDITOR/input-6CE-721-69BF0-4B2"
- pwa-fake-editor=""
>
Note: These attributes with
pwa-anddata-np-prefixes do not exist in the SSR HTML and appear to be injected on the client (likely by a browser extension). However, even in incognito/with extensions disabled, the main symptom ("task complete" without launching a browser) still occurs in production.
Proxy configuration (summary)
(I can share the full server block if helpful; sketch below)
server {
listen 443 ssl http2;
server_name example.mydomain.com;
# SSL ...
location / {
proxy_pass http://127.0.0.1:3000;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;
}
}What I have already tried
- ✅ Disable extensions and test in an incognito window.
- ✅ Clear browser cache and Next cache (
.next/). - ✅ Verify production environment variables.
- ✅ Ensure
X-Forwarded-Proto/Hostheaders are set in Nginx. - ✅ Test
NEXT_PUBLIC_SITE_URLwith the publichttps://...domain instead ofhttp://localhost:3000. - ✅ Inspect server and network logs in DevTools (no obvious failing request at the time “task complete” appears).
Additional context
- In local development (
pnpm dev) I can render the UI. The problem appears after deployment with Nginx+SSL. - The production domain is public and reachable (I can DM if needed). The hydration error shows attributes injected by extensions, but the primary symptom ("task complete" without launching a browser) also happens without extensions.
What I can provide
- Full Next server and Nginx logs
- Screenshots and network HAR
- Commit hash and sanitized
env
Diagnostic suggestions (if helpful)
- Force
NEXT_PUBLIC_SITE_URLto the public HTTPS URL and document this in theREADMEfor production. - Check whether
Date.now()/Math.random()/Intl.DateTimeFormatare used during SSR without serializing a snapshot. - Validate whether the event that should start the browser session is failing silently, and expose more explicit error/logging in the UI.
- Add environment checks for reverse proxy scenarios (e.g., trust
X-Forwarded-Proto).
Thanks for the project! I can test a patch/experimental branch if you point me to one. 🙏