SQLITE_PROTOCOLERRORTier 2 — Caution⚠️ MEDIUM confidenceDatabase locking protocol error
🔴 Production Risk Error
High — concurrent access may corrupt data if the locking protocol diverges.
What this means
SQLITE_PROTOCOL (15) indicates that SQLite detected a file locking protocol failure — another process used an incompatible locking protocol on the same database file.
Why it happens
- 1Two processes using different SQLite locking implementations on the same file.
- 2Custom VFS with non-compliant lock semantics.
- 3NFS or network filesystem not supporting mandatory locks correctly.
How to reproduce
Concurrent access from processes using different SQLite versions or custom VFS layers.
# Typically appears as:
# sqlite3.OperationalError: locking protocolFix 1
Why this works
Ensure all processes accessing the database file use a compatible SQLite version.
Fix 2
Why this works
Avoid using SQLite on NFS — use WAL mode on a local filesystem instead.
Fix 3
Why this works
If using a custom VFS, verify lock byte handling matches the SQLite spec.
What not to do
Why it's wrong:
Sources
📚 Official docs: https://www.sqlite.org/rescode.html#protocol
🔧 Source ref: sqlite3.h — SQLITE_PROTOCOL = 15
📖 Further reading: SQLite file locking and concurrency
Confidence assessment
⚠️ MEDIUM confidence
Stable.
See also
📄 Reference pages