database disk image is malformed

The database disk image is malformed error means SQLite detected corruption in your database file. This is serious but often recoverable.

Understanding the Error

SQLITE_CORRUPT: database disk image is malformed

The database file structure is damaged. SQLite can't reliably read or write data.

Common Causes

1. Interrupted Write Operations

Power loss or crash during a write:

App writing to database...
*POWER FAILURE*
Database left in inconsistent state

2. Disk Failures

Bad sectors or failing storage media.

3. Improper File Copying

Copying the database while it's being written:

# Dangerous if database is in use
cp myapp.db myapp-backup.db

4. Multiple Processes Without Proper Locking

Two processes writing without coordination.

5. NFS or Network Filesystem Issues

SQLite's locking doesn't work correctly on some network filesystems.

6. Memory Corruption

Bugs causing SQLite's memory structures to be overwritten.

7. Manually Editing the File

Opening the .db file in a text editor and saving.

How to Diagnose

Check Database Integrity

PRAGMA integrity_check;

Output for healthy database:

ok

Output for corrupted database:

*** in database main ***
Page 42: btree page corrupted
Page 108: invalid page number
row 1 missing from index users_email_idx

Quick Check

PRAGMA quick_check;  -- Faster but less thorough

How to Fix It

Solution 1: Restore from Backup

The safest option if you have a backup:

# Stop your application first
cp myapp-backup.db myapp.db

Solution 2: Export and Reimport

If the database is partially readable:

# Dump what you can
sqlite3 corrupt.db ".dump" > dump.sql

# Create new database
sqlite3 new.db < dump.sql

# Verify the new database
sqlite3 new.db "PRAGMA integrity_check;"

Solution 3: Use .recover Command

SQLite 3.29+ has a recovery mode:

sqlite3 corrupt.db ".recover" | sqlite3 recovered.db

This tries to extract data even from badly damaged databases.

Solution 4: Rebuild the Database

Copy all data to a new file:

-- Attach a new database
ATTACH DATABASE 'new.db' AS new_db;

-- Copy each table
CREATE TABLE new_db.users AS SELECT * FROM users;
CREATE TABLE new_db.posts AS SELECT * FROM posts;

-- Recreate indexes manually
DETACH DATABASE new_db;

Solution 5: Recover Specific Tables

If only some tables are corrupted:

-- Try to read each table
SELECT * FROM users;      -- Works?
SELECT * FROM posts;      -- Works?
SELECT * FROM comments;   -- Fails?

-- Export working tables
.mode insert
.output users_data.sql
SELECT * FROM users;

Solution 6: Use Third-Party Tools

Several tools specialize in SQLite recovery:

• DB Browser for SQLite (has recovery features)
• SQLite Database Recovery tools

Prevention

Enable WAL Mode

WAL mode is more resistant to corruption:

PRAGMA journal_mode=WAL;

Use Proper Backup Procedures

-- Safe backup using SQLite's backup API
VACUUM INTO 'backup.db';

-- Or use the backup command
sqlite3 myapp.db ".backup backup.db"

In application code:

// Node.js with better-sqlite3
const db = new Database('myapp.db');
db.backup('backup.db');

Enable Synchronous Writes

-- Safest (slower)
PRAGMA synchronous = FULL;

-- Good balance (default)
PRAGMA synchronous = NORMAL;

Avoid Network Filesystems

Don't put SQLite databases on:

• NFS mounts
• SMB/CIFS shares
• Some cloud-synced folders (Dropbox, OneDrive)

Implement Proper Shutdown

// Graceful shutdown
process.on('SIGTERM', () => {
  db.close();
  process.exit(0);
});

Regular Integrity Checks

// Check integrity periodically
const result = db.pragma('integrity_check');
if (result[0].integrity_check !== 'ok') {
  console.error('Database corruption detected!');
  // Alert, restore from backup, etc.
}

Best Practices

1. Regular backups - Test that you can restore them
2. Use WAL mode - Better crash recovery
3. Proper shutdown - Close database connections cleanly
4. Monitor disk health - Watch for failing drives
5. Don't use network filesystems - Use local storage
6. Run integrity checks - Catch problems early

Emergency Recovery Checklist

1. Stop all access to the database immediately
2. Make a copy of the corrupted file (don't modify original)
3. Check for backups - Recent backup is the safest fix
4. Try .recover command for partial recovery
5. Export what you can with .dump
6. Investigate the cause - Check logs, disk health

Related Errors

• SQLITE_NOTADB - File is not a database (completely wrong format)
• SQLITE_IOERR - Input/output error (disk issues)