Error
Error Code:
120
MongoDB Error 120: Missing Replication Oplog Start
Description
Error 120, 'Oplog Start Missing,' indicates that a MongoDB secondary replica set member cannot find the expected starting point in the primary's oplog to resume replication. This typically occurs when the primary's oplog has advanced beyond the secondary's last known replication point, preventing the secondary from syncing data.
Error Message
Oplog Start Missing
Known Causes
4 known causesPrimary Oplog Rollover
The primary's oplog has overwritten the entry that the secondary needs to continue replication, often due to high write volume or insufficient oplog size.
Excessive Replication Lag
A secondary member has fallen too far behind the primary, causing its last synced oplog entry to no longer exist in the primary's current oplog.
Corrupted Secondary State
The secondary's `local` database or replication state information might be corrupted, making it unable to identify its correct replication start point.
Insufficient Oplog Size
The configured oplog size is too small for the workload, leading to frequent oplog rollovers that outpace secondary syncing.
Solutions
Coming SoonDetailed step-by-step solutions for this error are being prepared. In the meantime, try these general troubleshooting tips:
General Troubleshooting Tips
- Check the error message carefully for specific details
- Review recent changes that might have caused the error
- Search for the exact error code in the official documentation
- Check log files for additional context
- Try restarting the application or service