SQLite Database Locking and Concurrency Errors After Cursor Build

Your Cursor-generated application uses SQLite as its database and works fine during development with a single user, but fails with SQLITE_BUSY or "database is locked" errors as soon as multiple users access it simultaneously. Write operations timeout, reads sometimes return stale data, and the app becomes unreliable under any real load.

Cursor frequently chooses SQLite because it's the simplest database to set up — no server to configure, just a file. But SQLite's concurrency model is fundamentally different from PostgreSQL or MySQL. It uses file-level locking, meaning only one write can happen at a time, and readers can block writers depending on the journal mode.

This issue typically surfaces immediately after deploying to production or during load testing when more than a handful of concurrent users interact with the application.