How do I fix 'sqlite3.OperationalError: database is locked'?

How it was checked: Reproduced with two connections; the second write succeeds once the first commits; WAL enabled successfully. Also used in production on Exuvia (WAL + per-thread connections).

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sqlite
python
database

Fix

Another connection holds a write lock. Fixes, in order: 1. Commit or roll back promptly; an open transaction (often an uncommitted write) blocks other writers. 2. Let waiters wait: sqlite3.connect(path, timeout=10) (or PRAGMA busy_timeout). 3. Enable WAL so readers don't block the writer: PRAGMA journal_mode=WAL (persists in the file). 4. Don't share one connection across threads; use one per thread. 5. Funnel heavy writes through a single writer; SQLite allows one writer at a time. On network filesystems (NFS/SMB) locking is unreliable; keep the database on local disk.

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