SQLite: database is locked (SQLITE_BUSY)

updated 2026-10-20

tool: SQLite
exit code: 0
versions: SQLite 3
os: any

SQLite allows many readers but only one writer at a time per database file. When a connection wants to write while another connection holds the write lock, SQLite returns SQLITE_BUSY, which drivers report as database is locked. With a busy timeout the second connection waits and retries; with a timeout of zero it fails at once.

Reproduce it

Two connections from Python's sqlite3 module; the first holds a write transaction, the second has timeout=0:

bash

python - <<'EOF'
import sqlite3
print("SQLite", sqlite3.sqlite_version)
a = sqlite3.connect("app.db", timeout=0)
a.execute("create table jobs (id integer primary key, state text)")
a.commit()
a.execute("begin immediate")
a.execute("insert into jobs (state) values ('new')")

b = sqlite3.connect("app.db", timeout=0)
try:
    b.execute("insert into jobs (state) values ('other')")
except sqlite3.OperationalError as e:
    print(f"{type(e).__name__}: {e} ({e.sqlite_errorname})")

a.commit()
b.execute("insert into jobs (state) values ('other')")   # works once the lock is released
b.commit()
print(b.execute("select count(*) from jobs").fetchone()[0], "rows")
EOF

Output

SQLite 3.53.1
OperationalError: database is locked (SQLITE_BUSY)
2 rows

Fixes

python

conn = sqlite3.connect("app.db", timeout=5)          # wait up to 5 s for the lock (Python's default is 5)
conn.execute("PRAGMA journal_mode=WAL")              # readers and one writer at the same time
with conn:                                            # commits, or rolls back on an exception
    conn.execute("insert into jobs (state) values (?)", ("new",))

Other drivers: PRAGMA busy_timeout = 5000; works in any connection, and most ORMs expose it as a connection option.

Sources

config · sqliteSQLite PRAGMA journal_mode=WAL: concurrent readers and a writerPRAGMA journal_mode=WAL makes SQLite write changes to a -wal file, so readers keep working while one connection writes. It is stored in the database file.compat · sqliteSQLite feature versions: RETURNING, STRICT, ->> and DROP COLUMNWhich SQLite version added what: DROP COLUMN 3.35, RETURNING 3.35, STRICT tables 3.37, the -> and ->> JSON operators 3.38, unixepoch() 3.38, concat_ws() 3.44.glossary · sqlWhat is a database index?A database index is a sorted structure, usually a B-tree, that finds rows by column value without reading the whole table, at the cost of slower writes.

Reproduce it

Fixes

Sources

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