Signal keeps crashing: table message_fts already exists

• I have searched open and closed issues for duplicates
• I am submitting a bug report for existing functionality that does not work as intended
• I have read https://github.com/signalapp/Signal-Android/wiki/Submitting-useful-bug-reports
• This isn't a feature request or a discussion topic

Bug description

Signal crashes immediately upon startup. I checked the logs from adb logcat, and I see this backtrace:

08-11 18:08:00.626  5846  5885 E SignalUncaughtException: android.database.sqlite.SQLiteException: FullCode: 1 | ErrorCode: 1 | ExtendedErrorCode: 0 | Message: table message_fts already exists | ExtraMessage: , while compiling: CREATE VIRTUAL TABLE message_fts USING fts5(body, thread_id UNINDEXED, content=message, content_rowid=_id)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteConnection.nativePrepareStatement(Native Method)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:925)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteConnection.prepare(SQLiteConnection.java:536)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteSession.prepare(SQLiteSession.java:592)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteProgram.<init>(SQLiteProgram.java:64)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteStatement.<init>(SQLiteStatement.java:38)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteDatabase.executeSql(SQLiteDatabase.java:1991)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteDatabase.execSQL(SQLiteDatabase.java:1900)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.helpers.migration.V175_FixFullTextSearchLink.migrate(V175_FixFullTextSearchLink.kt:18)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.helpers.SignalDatabaseMigrations.migrate(SignalDatabaseMigrations.kt:177)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.SignalDatabase.onUpgrade(SignalDatabase.kt:170)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:403)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at net.zetetic.database.sqlcipher.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:302)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.SignalDatabase.getRawReadableDatabase(SignalDatabase.kt:195)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.SignalDatabase$Companion.hasTable(SignalDatabase.kt:311)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.SignalDatabase.hasTable(SignalDatabase.kt:0)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.JobDatabase.dropTableIfPresent(JobDatabase.java:377)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.JobDatabase.lambda$onOpen$0(JobDatabase.java:148)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.JobDatabase.$r8$lambda$mPCnH21FLj07HGuB-BTTkoK77eM(JobDatabase.java:0)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.thoughtcrime.securesms.database.JobDatabase$$ExternalSyntheticLambda7.run(R8$$SyntheticClass:0)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at java.lang.Thread.run(Thread.java:923)
08-11 18:08:00.626  5846  5885 E SignalUncaughtException: 	at org.signal.core.util.concurrent.SignalExecutors$NumberedThreadFactory$1.run(SignalExecutors.java:109)
08-11 18:08:00.627  5846  5889 I SQLiteConnection: Database keying operation returned:0
08-11 18:08:00.647  5846  5917 W JobController: [JOB::084a1674-2d69-40cf-83ec-b5ad959d26e2][RefreshSvrCredentialsJob] Already at the max instance count. Factory limit: -1, Queue limit: 2. Skipping. (Time Since Submission: 1 ms, Lifespan: 86400000 ms, Run Attempt: 1/3, Queue: RefreshKbsCredentials)
08-11 18:08:00.648  5846  5917 I EmojiSearchIndexDownloa: Need to check. It's been 35255292838 ms since the last check.
08-11 18:08:00.649  5846  5917 W JobController: [JOB::a6fecd33-228a-4413-9c70-7f7e382776b8][EmojiSearchIndexDownloadJob] Already at the max instance count. Factory limit: 2, Queue limit: -1. Skipping. (Time Since Submission: 1 ms, Lifespan: 86400000 ms, Run Attempt: 1/Unlimited, Queue: EmojiSearchIndexDownloadJob)
08-11 18:08:00.666  5846  5889 I SQLiteConnection: Database keying operation returned:0
08-11 18:08:00.676  5846  5889 I SignalDatabase: Upgrading database: 155, 201
08-11 18:08:00.693  5846  5885 I JobManager: Successfully flushed.
08-11 18:08:00.694  5846  5885 I Process : Sending signal. PID: 5846 SIG: 9
08-11 18:08:00.755  1356  3337 D ConnectivityService: ConnectivityService NetworkRequestInfo binderDied(NetworkRequest [ TRACK_DEFAULT id=419, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Uid: 10288 AdministratorUids: [] RequestorUid: 10288 RequestorPackageName: org.thoughtcrime.securesms] ], android.os.BinderProxy@c989b2f)
08-11 18:08:00.756  1356  2163 I ActivityManager: Process org.thoughtcrime.securesms (pid 5846) has died: cch+5 CEM 
08-11 18:08:00.757  1356  1383 I libprocessgroup: Successfully killed process cgroup uid 10288 pid 5846 in 0ms
08-11 18:08:00.757  1356  1519 D ConnectivityService: releasing NetworkRequest [ TRACK_DEFAULT id=419, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Uid: 10288 AdministratorUids: [] RequestorUid: 10288 RequestorPackageName: org.thoughtcrime.securesms] ] (release request)
08-11 18:08:00.757   624   624 I Zygote  : Process 5846 exited due to signal 9 (Killed)

Steps to reproduce

• Tap to open signal

Actual result: Describe here what happens after you run the steps above (i.e. the buggy behaviour)

• Signal crashes

Expected result: Describe here what should happen after you run the steps above (i.e. what would be the correct behaviour)

• Signal opens

Screenshots

Device info

Device: LG K62
Android version: 11
Signal version: 6.28.6

Link to debug log

Impossible to open signal

Start with the CREATE VIRTUAL TABLE failure in app/src/main/java/org/thoughtcrime/securesms/database/helpers/migration/V175_FixFullTextSearchLink.kt at line 18, then read SignalDatabaseMigrations.kt and SignalDatabase.kt around the migration and upgrade calls. Use the reported Android 11 startup path as the reproduction case; done means the existing message_fts table no longer causes Signal to crash during startup.