## Issue
I'm getting a **500 Internal Server Error** ("There's a problem loading this page") when trying to install a Custom App created in the new **Dev Dashboard**. The error happens on the app grant/authorization page, before any permission confirmation is shown.
## App Configuration
This app is intended to be **App Proxy only** — it does not need an Admin UI, OAuth session, or embedded app interface. It only needs `write_app_proxy` scope so that Shopify can proxy storefront requests to my external Cloudflare Worker.
| Setting | Value |
|---|---|
| App type | Custom App (Dev Dashboard) |
| Distribution | Custom (single store) |
| `embedded` | `false` |
| `use_legacy_install_flow` | `false` (Shopify managed install) |
| Scopes | `write_app_proxy` |
| App URL (first attempt) | `https://customer-signup-event-service.customer-signup-service.workers.dev` (returns JSON `{"ok":true}`) |
| App URL (second attempt) | `https://shopify.dev/apps/default-app-home` |
| Redirect URLs | empty |
| App Proxy | configured: prefix=`apps`, subpath=`cse-bind-token`, url=`https://customer-signup-event-service.customer-signup-service.workers.dev/attribution/bind-token` |
| Webhooks API version | `2026-07` |
## What I've Tried
1. **First attempt**: App URL pointed to my Cloudflare Worker (returns JSON). Install → 500 error.
2. **Second attempt**: Changed App URL to `https://shopify.dev/apps/default-app-home` (Shopify's official default app home for extension-only apps), released a new version, reinstalled → still 500.
3. Confirmed the Worker is running and reachable.
4. Confirmed the Shopify store admin works normally (not a store-side issue).
5. Refreshed and retried multiple times over ~1 hour.
6. Checked Shopify status page — no reported incidents.
## Error URL Pattern
The 500 occurs at: