.NET 8, Web Assembly Deploy Gets "No such file or directory" error on Heroku

[RobertMeakin]

BlazorWebAssembly on net8.0.

I add the correct buildpack and run git push heroku main.

The console shows it building as expected (with the correct .Net version) but in the Heroku, Application Logs, I get the following.

2024-06-24T20:09:30.000000+00:00 app[api]: Build succeeded
2024-06-24T20:12:31.370830+00:00 heroku[web.1]: State changed from crashed to starting
2024-06-24T20:12:39.920961+00:00 heroku[web.1]: Starting process with command `cd /app/heroku_output && ./{ProjectName}`
2024-06-24T20:12:40.549831+00:00 heroku[web.1]: Process exited with status 127
2024-06-24T20:12:40.491794+00:00 app[web.1]: /bin/bash: line 1: ./{ProjectName}: No such file or directory
2024-06-24T20:12:40.574303+00:00 heroku[web.1]: State changed from starting to crashed

Any help is much appreciated.

[jincod]

Hello @RobertMeakin

Have you checked https://github.com/search?q=repo%3Ajincod%2Fdotnetcore-buildpack+blazor&type=issues and especially #75 (comment)?

[RobertMeakin]

Hi,
This was the problem:

The output for Blazor WASM is static files (wwwroot), not .net core app.
Here

This surprised me because this online tutorial makes no mention of this:
Deploy your C# aspnet core Application free hosting To Heroku Step by Step -2022

My solution was to add a separate node app with express that would serve the static files in wwwroot.
In a separate folder (at the same level as the folder containing the web assembly project):

npm init -y
npm install express

node_server/index.js :

  const express = require('express');
  const path = require('path');
  const app = express();

  app.use(express.static(path.join(__dirname, '../wwwroot')));

  const PORT = process.env.PORT || 3000;
  app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
  });

Procfile:
web: node node_server/index.js

Then write a bash script that would take care of running dotnet publish -c Release -o release, copy the wwwroot folder to the express app and push to heroku.