Common Local DB Failures

Symptom	Likely cause	Fix
app crashes after update	missing migration path	add migration from old version and test with fixture
data disappeared after upgrade	destructive migration ran	restore backup, remove fallback for user data
backup misses latest rows	copied `.db` without WAL	use online backup API or `VACUUM INTO`
database is locked	long transaction or another process	shorten transactions, close readers, add timeout/retry
restore opens but data is wrong	imported unsupported version or partial files	validate manifest, schema, checksums, and row counts
search results stale	derived index not rebuilt	rebuild index from source data after import/migration
browser write fails	quota exceeded	show cleanup/export UX and request persistent storage
IndexedDB upgrade hangs	old tab holds DB connection	prompt reload/close other tabs

SQLite Triage

PRAGMA database_list;
PRAGMA integrity_check;
PRAGMA foreign_key_check;
PRAGMA journal_mode;

confirm the installed app version and DB version
check exported schema history
reproduce with an old fixture DB
assert migration preserved representative rows
inspect the device DB with Android Studio Database Inspector or adb shell sqlite3