How to fix SQLITE_NOTADB: File opened that is not a database file in SQLite

# Linux/macOS: Check file signature
hexdump -C your_database.db | head -1
# Should show: 53 51 4c 69 74 65 20 66 6f 72 6d 61 74 20 33

# Alternative: Use file command
file your_database.db
# Should output: SQLite 3.x database

# Or check the first bytes with od
od -c your_database.db | head -1
# Should start with: S q l i t e   f o r m a t   3

# List the file
ls -lh /path/to/your_database.db

# Check file type
file /path/to/your_database.db

# Verify the path in your application configuration
cat your_app_config.json | grep database
# or
grep DATABASE_PATH .env

// Node.js with better-sqlite3 and sql.js (encrypted)
const Database = require('better-sqlite3');
const db = new Database('encrypted.db');

// For encrypted databases, must set key BEFORE any operations
try {
  db.pragma('key = "yourpassword"');
  db.prepare('SELECT 1').get(); // Test if key works
} catch (err) {
  console.error('Wrong password or not an encrypted database:', err.message);
}

# Python with sqlcipher
import sqlcipher3 as sqlite3

conn = sqlite3.connect('encrypted.db')
conn.execute('PRAGMA key="yourpassword"')
conn.execute('SELECT 1')  # Test if key is correct

// C API with SQLCipher
sqlite3 *db;
int rc = sqlite3_open("encrypted.db", &db);

if (rc == SQLITE_OK) {
  // Set key BEFORE any other operations
  const char *key = "mypassword";
  sqlite3_key(db, key, strlen(key));

  // Test if key is correct
  char *errMsg = NULL;
  rc = sqlite3_exec(db, "PRAGMA integrity_check;", NULL, NULL, &errMsg);
  if (rc != SQLITE_OK) {
    printf("Wrong password: %s\n", errMsg);
  }
}

# Try to recover the database
sqlite3 corrupted.db ".recover" > recovered.sql

# If .recover is not available (older SQLite), try .dump
sqlite3 corrupted.db ".dump" > recovered.sql

# Inspect the recovered SQL
head -50 recovered.sql

# Create new database from recovered SQL
sqlite3 recovered.db < recovered.sql

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

# Open database and check integrity
sqlite3 your_database.db "PRAGMA integrity_check;"

# More detailed check
sqlite3 your_database.db "PRAGMA integrity_check(10000);"
# Returns list of corruption types found

# Check quick integrity (faster but less thorough)
sqlite3 your_database.db "PRAGMA quick_check;"

# Check specific table
sqlite3 your_database.db "PRAGMA integrity_check(your_table);"

# Check if backup exists
ls -la *.db *.bak *.backup

# Restore from backup
cp your_database.db.backup your_database.db

# Verify the restored database
sqlite3 your_database.db "PRAGMA integrity_check;"

# Test database operations
sqlite3 your_database.db "SELECT COUNT(*) FROM main_table;"

# Check file permissions
ls -l your_database.db

# Ensure current user can read the file
chmod 644 your_database.db  # rw- r-- r--

# Check if disk is full (can cause corruption)
df -h /path/to/your_database.db

# Check disk health
# Linux:
smartctl -a /dev/sda  # Check SSD/HDD health
dmesg | grep -i error  # Check system logs

# macOS:
diskutil info /Volumes/YourDrive

# Extract readable data from corrupted file
strings corrupted.db | grep -E "^[A-Z_]+" > extracted_data.txt

# Use specialized SQLite recovery tools
# Online tools like DBRecovery or DataRecovery can sometimes recover data
# Download from: https://www.stellarinfo.com/sqlite-repair.php

# If database was previously exported as SQL, restore from that
sqlite3 new_database.db < exported_backup.sql

# Manually check if there are .wal or .shm files (Write-Ahead Log)
ls -la your_database.db*
# If found: your_database.db-wal or your_database.db-shm
# These might contain recent transactions that can be recovered