NOT NULL constraint failed

Category: ConstraintVersions: 3.8.0+

🔴 Production Risk Error

Low — fails immediately with a clear message.

What this means

SQLITE_CONSTRAINT_NOTNULL (1299) is returned when a NULL value is inserted or updated into a column declared as NOT NULL.

Why it happens

1Passing None/NULL to a NOT NULL column.
2Missing column in INSERT statement that has no DEFAULT value and is NOT NULL.
3Application bug producing None for a required field.

How to reproduce

INSERT or UPDATE with a NULL value in a NOT NULL column.

trigger — this will ERROR

import sqlite3
conn = sqlite3.connect(':memory:')
conn.execute('CREATE TABLE users(name TEXT NOT NULL, email TEXT NOT NULL)')
try:
    conn.execute('INSERT INTO users(name, email) VALUES(?, ?)', ('Alice', None))
except sqlite3.IntegrityError as e:
    print(e)  # NOT NULL constraint failed: users.email

sqlite3.IntegrityError: NOT NULL constraint failed: users.email

Fix 1

Why this works

Provide a non-NULL value or a default: ALTER TABLE users ALTER COLUMN email SET DEFAULT ''

Fix 2

Why this works

Add application-level validation to catch None before the INSERT.

Sources

📚 Official docs: https://www.sqlite.org/rescode.html#constraint_notnull

🔧 Source ref: sqlite3.h — SQLITE_CONSTRAINT_NOTNULL = 1299

Confidence assessment

⚠️ MEDIUM confidence

Stable.