[BUG] 500 Internal Server Error in preview and no way to debug

[mohsentaleb]

When I develop my nextjs app locally with npm run dev everything is working fine but after running npm run preview (opennextjs-cloudflare build && opennextjs-cloudflare preview -- --remote) although the app gets built successfully, when I open the browser at the home page I get the following 500 Internal Server Error:

� Starting asset upload...
� Found 1 new or modified static asset to upload. Proceeding with upload...
+ /BUILD_ID
Uploaded 1 of 1 assets
✨ Success! Uploaded 1 file (244 already uploaded) (1.43 sec)

[wrangler:info] GET / 500 Internal Server Error (9708ms)
[wrangler:info] GET / 500 Internal Server Error (45067ms)
[wrangler:info] GET / 500 Internal Server Error (32660ms)
[wrangler:info] GET /.well-known/appspecific/com.chrome.devtools.json 500 Internal Server Error (78ms)
[wrangler:info] GET /_next/static/W-kpwAXFcYrYjnKyDlvcA/_ssgManifest.js 200 OK (127ms)
[wrangler:info] GET /_next/static/W-kpwAXFcYrYjnKyDlvcA/_buildManifest.js 200 OK (139ms)
[wrangler:info] GET /favicon.ico 304 Not Modified (76ms)
[wrangler:info] GET / 500 Internal Server Error (68ms)
[wrangler:info] GET /.well-known/appspecific/com.chrome.devtools.json 500 Internal Server Error (79ms)
[wrangler:info] GET /favicon.ico 304 Not Modified (70ms)

There's also no way I can debug the app in this mode.

Steps to reproduce

1. Get the app in preview mode
2. Open browser at http://localhost:8787/
3. There's no way server (worker) errors are printed to console. (with npm run dev app is working fine)

Expected behavior

Preferably there should be a way to see app errors in preview mode (as the name suggests we're previewing it and developer can still be notified of the code errors)

@opennextjs/cloudflare version

1.2.1

Wrangler version

4.19.1

next info output

� Starting asset upload...
� Found 1 new or modified static asset to upload. Proceeding with upload...
+ /BUILD_ID
Uploaded 1 of 1 assets
✨ Success! Uploaded 1 file (244 already uploaded) (1.43 sec)

[wrangler:info] GET / 500 Internal Server Error (9708ms)
[wrangler:info] GET / 500 Internal Server Error (45067ms)
[wrangler:info] GET / 500 Internal Server Error (32660ms)
[wrangler:info] GET /.well-known/appspecific/com.chrome.devtools.json 500 Internal Server Error (78ms)
[wrangler:info] GET /_next/static/W-kpwAXFcYrYjnKyDlvcA/_ssgManifest.js 200 OK (127ms)
[wrangler:info] GET /_next/static/W-kpwAXFcYrYjnKyDlvcA/_buildManifest.js 200 OK (139ms)
[wrangler:info] GET /favicon.ico 304 Not Modified (76ms)
[wrangler:info] GET / 500 Internal Server Error (68ms)
[wrangler:info] GET /.well-known/appspecific/com.chrome.devtools.json 500 Internal Server Error (79ms)
[wrangler:info] GET /favicon.ico 304 Not Modified (70ms)

Additional context

No response

[techlism]

I have tried to deploy it on workers and got the same white screen stating Internal Server Error

[vicb]

Could you create a minimal repro (link to a GH repository?)
Thanks