Test Mode repeatedly stalls at "Finalizing project setup" after compilation

[business853]

Can we access your project?

• I give permission for members of the FlutterFlow team to access and test my project for the sole purpose of investigating this issue.

Current Behavior

Project: BEFORE
Project ID: before-jm3x4r

A fresh Test Mode sandbox compiles and advances normally through code generation and sandbox creation, but then remains indefinitely at "Finalizing project setup." The UI states that setup typically takes under one minute, but the latest session remained there for more than four minutes and never rendered the app.

Latest affected session:

• Session ID: a1d6654e-82ae-4f56-8da7-270e4cc16c4d
• URL: https://app.flutterflow.io/debug/before-jm3x4r/a1d6654e-82ae-4f56-8da7-270e4cc16c4d?sandbox=1
• Tested: August 30, 2026

Previous clean session with the same failure:

• Session ID: 3453882d-bdc8-4bc9-a201-3a8983ce5c1f

No FlutterFlow project compilation or app runtime error is displayed. Available console messages are environment-level warnings: WebGL is unavailable and rendering falls back to CPU; Google Maps JavaScript API loading is not asynchronous; and browser-extension metadata messages.

Expected Behavior

After compilation and sandbox creation complete, Test Mode should finish finalizing and render the app so the authenticated user can interact with the BEFORE project.

Steps to Reproduce

1. Open project BEFORE (project ID: before-jm3x4r) in the FlutterFlow web editor.
2. Confirm the project is synchronized.
3. Start a fresh Test Mode session.
4. Allow code generation and sandbox creation to complete without reloading or restarting.
5. Observe that the process reaches "Finalizing project setup."
6. Wait at least four minutes.
7. Observe that the app never renders and no project compilation/runtime error appears.
8. End the temporary session and repeat with a clean Test Mode session; the same stall occurs.

Reproducible from Blank

• The steps to reproduce above start from a blank project.

Bug Report Code (Required)

ITFXlvHl04lPm9hE1ZCIY8ZGnikwGVAbUOc7j9VEGAsjCeP0POxzP/TBaldWUsyrdkFlMESmmj0BpvyKiOPXIMYqKQeaY6E6zKp+chXwLViVa5OBCrWaZnZ6M8VPCGrE0rWvuyN5APVpWmwj3161et+9TgXAJ5O3ImdISq/LZO4=

Visual documentation

The Test Mode screen remains on:
"Creating sandbox environment..."
"Finalizing project setup..."
"This typically takes under a minute"

Latest session evidence:
https://app.flutterflow.io/debug/before-jm3x4r/a1d6654e-82ae-4f56-8da7-270e4cc16c4d?sandbox=1

Environment

- FlutterFlow version: Current production web editor as of August 30, 2026
- Platform: Web
- Browser name and version: Chrome cloud browser (exact version not exposed)
- Operating system and version affected: Managed cloud-browser environment (exact OS version not exposed)

Additional Information

This blocks the remaining read-only MVP smoke tests for Add Reminder notification defaults and Reminder Details overflow.

Troubleshooting already completed:

• Reloaded one stalled sandbox once; it recompiled and stalled at the same point.
• Ended only the temporary stalled session and launched clean replacement sessions.
• Retried after several hours and after reauthenticating to FlutterFlow.
• Verified the generated Dart code and the four existing notification-switch bindings.
• Confirmed the project is synchronized and no app compilation error is reported.
• No incognito session was used because the failure occurs after cloud sandbox compilation.

A similar historical report exists at #5364, but it was closed in January 2025 after that reporter said the issue resolved itself. This project continues to reproduce the failure across multiple clean sessions.

[bhavesayali-debug]

I am also facing the same issue with my test environment

[eappling22-glitch]

Same issue here:

That flutterflow-io-6f20 project is FlutterFlow's own internal Firestore backend (not your app's Firebase project) — it's what they use to coordinate provisioning your sandbox test environment. It's returning 503 Service Unavailable, intermittently, which is exactly why the loading screen keeps retrying and never resolves: the retry loop I saw in your Network tab (all those repeated channel?gsessionid=... requests) is the client backing off and reconnecting after each failed attempt.

[inmersionfinanciera2025-commits]

Same issue here on a production FlutterFlow project.

New Test Mode remains indefinitely at:
Creating sandbox environment... / Finalizing project setup...

I inspected Chrome DevTools during troubleshooting.

Initially, the sandbox provisioning request:
POST https://sandbox-ygxkweukma-uc.a.run.app/api/sandboxes
returned 500 Internal Server Error.

After retrying, the same endpoint started returning 200/204, and Network currently shows no blocking 4xx/5xx responses, but Test Mode still never renders the application.

Console only shows the Google Maps JavaScript API loading=async performance warning; no application compilation/runtime error is shown.

This project previously used New Test Mode normally and the issue started recently.

This appears consistent with an intermittent FlutterFlow sandbox/backend provisioning issue rather than the application itself.

[Alezanello]

Hello everyone!

Thanks for the report! I’m going to tag our engineering team internally so they can take a closer look at these cases. I wasn’t able to replicate the issue on my end, but it’s clearly affecting your side, so we’ll have them investigate further.

Thanks for your patience and understanding!