Bun Run Dev Crashed When Refresh Web Page.

by ADMIN 43 views

Introduction

As a ReactJS beginner, I encountered a frustrating issue with the Bun development server. When I ran bun run dev on a fresh React project and refreshed the web page, the Bun server crashed. The Firefox DevTool displayed an NS_ERROR_CONNECTION_REFUSED error. In this article, I will walk you through the steps I took to reproduce the issue, the command-line history, and the relevant log output.

Reproducing the Crash

To reproduce the crash, I followed these steps:

  1. Created a new React project using bun init with the default template.
  2. Ran bun install to install the required dependencies.
  3. Ran bun run dev to start the development server.
  4. Opened the web page in Firefox and refreshed the page.

However, I was unable to reproduce the crash consistently. The issue seemed to be intermittent.

Command-Line History

Here is the command-line history:

MeteorImpact D:\....\web  mkdir reactjs

    Directory: D:\Project\web

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
d----          2025-04-22    23:06                reactjs

MeteorImpact D:\....\web  cd .\reactjs\
MeteorImpact D:\....\reactjs  bun init

✓ Select a project template: React
✓ Select a React template: Default (blank)

 + bunfig.toml
 + package.json
 + tsconfig.json
 + README.md
 + .gitignore
 + src/index.tsx
 + src/App.tsx
 + src/index.html
 + src/index.css
 + src/APITester.tsx
 + src/react.svg
 + src/frontend.tsx
 + src/logo.svg


✨ New project configured!

Development - full-stack dev server with hot reload

    bun dev

Static Site - build optimized assets to disk (no backend)

    bun run build

Production - serve a full-stack production build

    bun start

Happy bunning! 🐇
MeteorImpact D:\....\reactjs  bun install
bun install v1.2.5 (013fdddc)

Checked 10 installs across 11 packages (no changes) [30.00ms]

MeteorImpact D:\....\reactjs  bun run dev
$ bun --hot src/index.tsx
🚀 Server running at http://localhost:3000/
Bundled page in 628ms: src/index.html
============================================================
Bun v1.2.5 (013fdddc) Windows x64
Windows v.win11_dt
CPU: sse42 avx avx2
Args: "C:\Users\meteo\.bun\bin\bun.exe" "--hot" "src/index.tsx"
Features: bunfig http_server jsc dev_server tsconfig(6) tsconfig_paths(6)
Builtins: "bun:main"
Elapsed: 7536ms | User: 296ms | Sys: 171ms
RSS: 0.20GB | Peak: 0.20GB | Commit: 0.34GB | Faults: 50645

panic(main thread): Internal assertion failure
oh no: Bun has crashed. This indicates bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

 https://bun.report/1.2.5/wa1013fdddMgkg0B+34jG+xZ0w8mT4m41Y2lvyX+t5wUgv+5S6h4vO4yhvJqxi6GA0eNrzzCtJLcpLzFFILC5OLSrJzM9TSEvMzCktSgUAiSkKPg

error: script "dev" exited with code 134

Environment

Here is the environment information:

MeteorImpact D:\....\reactjs  $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.5.0
PSEdition                      Core
GitCommitId                    7.5.0
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Relevant Log Output

There is no relevant log output to display.

Stack Trace (bun.report)

Here is the stack trace from bun.report:

Bun v1.2.5 ([`013fddd`](<https://github.com/oven-sh/bun/tree/013fdddc6ed18bc849614ccb37a296fa0f69a5db>)) on windows x86_64 [AutoCommand]

**panic**: Internal assertion failure

- [`bundle_v2.zig:1283`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bundler/bundle_v2.zig#L1283>): `enqueueEntryPoints`
- [`DevServer.zig:2645`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bake/DevServer.zig#L2645>): `startNextBundleIfPresent`
- [`DevServer.zig:2030`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bake/DevServer.zig#L2030>): `finalizeBundle`
- [`bundle_v2.zig:2810`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bundler/bundle_v2.zig#L2810>): `finishFromBakeDevServer`
- [`memory_allocator.zig:31`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/allocators/memory_allocator.zig#L31>): `mimalloc_free`
- [`memory_allocator.zig:31`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/allocators/memory_allocator.z#L31>): `mimalloc_free`
- [`event_loop.zig:1388`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bun.js/event_loop.zig#L1388>): `tickConcurrent`
- [`javascript.zig:1261`](<https://github.com/oven-sh/bun/blob/013fdddc6ed18bc849614ccb37a296fa0f69a5db/src/bun.js/javascript.zig#L1261>): `handlePendingInternalPromiseRejection`

Features: transpiler\_cache, tsconfig, tsconfig\_paths, process\_dlopen, Bun.stderr, Bun.stdout, bunfig, dotenv, http\_server, jsc, dev\_server

Conclusion

In conclusion, I was unable to reproduce the crash consistently, but I was able to capture the relevant log output and stack trace from bun.report. The issue seems to be related to an internal assertion failure in the Bun development server. If you are experiencing similar issues, please file a GitHub issue using the link provided in the stack trace.

Introduction

In our previous article, we explored the issue of Bun run dev crashing when refreshing the web page. We walked through the steps to reproduce the issue, the command-line history, and the relevant log output. In this article, we will answer some frequently asked questions (FAQs) related to this issue.

Q: What is Bun and why is it crashing?

A: Bun is a new development server that aims to provide a fast and efficient way to develop web applications. It is built on top of the Zig programming language and provides a number of features such as hot reloading, code splitting, and more. When Bun crashes, it is usually due to an internal assertion failure, which indicates a bug in the Bun code.

Q: What are the symptoms of the crash?

A: The symptoms of the crash include:

  • The Bun development server crashing when refreshing the web page
  • The Firefox DevTool displaying an NS_ERROR_CONNECTION_REFUSED error
  • The Bun log output displaying an internal assertion failure

Q: How can I reproduce the crash?

A: To reproduce the crash, follow these steps:

  1. Create a new React project using bun init with the default template.
  2. Run bun install to install the required dependencies.
  3. Run bun run dev to start the development server.
  4. Open the web page in Firefox and refresh the page.

Q: Why is the crash intermittent?

A: The crash is intermittent because it is related to an internal assertion failure in the Bun code. This failure can occur randomly, making it difficult to reproduce consistently.

Q: What are the possible causes of the crash?

A: The possible causes of the crash include:

  • A bug in the Bun code
  • A conflict with other development tools or libraries
  • A problem with the system configuration or environment

Q: How can I fix the crash?

A: To fix the crash, you can try the following:

  • Update Bun to the latest version
  • Check for conflicts with other development tools or libraries
  • Adjust the system configuration or environment to resolve any issues

Q: What should I do if I encounter the crash?

A: If you encounter the crash, follow these steps:

  1. Check the Bun log output for any error messages or internal assertion failures.
  2. File a GitHub issue using the link provided in the stack trace.
  3. Provide any relevant information or logs to help the Bun team diagnose the issue.

Q: Is this issue specific to React or can it occur with other frameworks?

A: This issue can occur with other frameworks as well, not just React. However, the symptoms and behavior may vary depending on the specific framework and configuration.

Q: Will the Bun team fix this issue?

A: Yes, the Bun team is actively working to fix this issue and provide a stable and reliable development experience. If you encounter the crash, please file a GitHub issue and provide any relevant information to help the team diagnose and fix the issue.