Bun 1.2 in Production: What Actually Broke When We Migrated from Node

Bun 1.2 in Production: What Actually Broke When We Migrated from Node We migrated a mid-size TypeScript API (Next.js backend routes + a standalone Express-equivalent service) from Node 20 to Bun 1.2 over three weeks. The marketing copy says "drop-in replacement." Here's what that actually means in practice. What We Were Running A Next.js 14 app (stayed on Node — Next.js doesn't officially support Bun runtime yet for SSR) A standalone API service: Hono + Drizzle ORM + Postgres Several background