# MongoServerError: CappedCollection: invalid oplog entry with timestamp { ts: Timestamp(0, 0) }

- **ID:** `mongodb/capped-collection-invalid-oplog`
- **Domain:** mongodb
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 85%

## Root Cause

The oplog contains a corrupted entry with a zero timestamp, likely due to a disk write error or improper shutdown.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| MongoDB 5.0 | active | — | — |
| MongoDB 6.0 | active | — | — |
| MongoDB 7.0 | active | — | — |

## Workarounds

1. **Restart the MongoDB instance with --repair to reconstruct the oplog: mongod --repair --dbpath /var/lib/mongodb** (80% success)
   ```
   Restart the MongoDB instance with --repair to reconstruct the oplog: mongod --repair --dbpath /var/lib/mongodb
   ```
2. **If the node is a secondary, resync from the primary by deleting the local database files and restarting: rm -rf /var/lib/mongodb/local/* && systemctl restart mongod** (95% success)
   ```
   If the node is a secondary, resync from the primary by deleting the local database files and restarting: rm -rf /var/lib/mongodb/local/* && systemctl restart mongod
   ```
3. **Use mongodump with --oplog to export the oplog, then drop and re-import to clean corrupted entries: mongodump --db local --collection oplog.rs --out /tmp/oplog_backup; mongo local --eval 'db.oplog.rs.drop()'; mongorestore --db local --collection oplog.rs /tmp/oplog_backup/local/oplog.rs.bson** (85% success)
   ```
   Use mongodump with --oplog to export the oplog, then drop and re-import to clean corrupted entries: mongodump --db local --collection oplog.rs --out /tmp/oplog_backup; mongo local --eval 'db.oplog.rs.drop()'; mongorestore --db local --collection oplog.rs /tmp/oplog_backup/local/oplog.rs.bson
   ```

## Dead Ends

- **** — The oplog is a special collection; manual deletion corrupts the storage engine state. (90% fail)
- **** — repairDatabase is not designed for internal system collections like oplog. (80% fail)
- **** — The corrupted entry remains in the oplog file after restart. (70% fail)