Bun FormData Bug Reproduction (Issue #2644)

Summary

This repository reproduces both the original "FormData missing final boundary" error AND the framework integration issues reported in GitHub issue #2644.

GitHub Issue: oven-sh/bun#2644

✅ Successfully Reproduced

1. The Original "Missing Final Boundary" Error

✅ REPRODUCED - The exact error from the GitHub issue:

FormData parse error missing final boundary

Triggers: Malformed FormData with:

• Missing final --boundary-- marker
• Truncated boundary strings
• Empty body with boundary header
• Mismatched boundaries (header vs body)

2. Hono Framework - Different Error

When using Hono v4.9.4, a different but related error occurs:

TypeError: undefined is not a function (near '...entry of iterable...')
      at fromEntries (native:7:20)

Affected Frameworks

Based on GitHub issue comments:

• Hono ✅ (confirmed in this reproduction)
• Astro
• SvelteKit
• SolidStart
• Qwik

Quick Reproduction

Option 1: Original "Missing Final Boundary" Error

bun create-malformed-boundary.js

Expected: Multiple "FormData parse error missing final boundary" errors

Option 2: Framework Integration Issues

1. Install dependencies: bun install
2. Start Hono server: bun run server
3. Run test: bun run test Expected: 100% failure rate with iterator errors

Root Cause

The issue appears to be that FormData.entries() returns an invalid iterator when accessed through framework request wrappers, while working correctly in vanilla Bun servers.

Files

Primary Reproductions

• create-malformed-boundary.js - ✅ Reproduces original "missing final boundary" error
• reproduce-2644-hono.js - Hono framework integration issues

Additional Tests

• test-aggressive-2644.js - Concurrent FormData test client
• reproduce-2644-original.js - Original issue reproduction attempt
• reproduce-2644-cloning.js - Request cloning/wrapping tests
• reproduce-2644-boundary.js - Boundary-focused tests
• test-client-2644.js - Basic FormData tests

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This reproduction confirms that FormData parsing is completely broken when using popular JavaScript frameworks with Bun, making it unusable for real-world applications that rely on form submissions.