Error
Error Code:
96
MongoDB Error 96: Generic Operation Failure
Description
Error 96, 'Operation Failed', is a generic MongoDB error indicating that a database operation could not be completed successfully. This error typically occurs when an underlying issue prevents the server from executing a requested command, without providing a more specific error code.
Error Message
Operation Failed
Known Causes
4 known causesInsufficient User Permissions
The authenticated user lacks the necessary read or write privileges to perform the requested operation on the target database or collection.
Network Connectivity Problems
The client application lost connection to the MongoDB server, or there's an intermittent network disruption preventing successful communication.
Server Resource Exhaustion
The MongoDB server or its host machine might be experiencing high CPU, memory, or disk I/O, leading to the operation timing out or failing.
MongoDB Server Misconfiguration
The MongoDB server might be configured incorrectly, or a critical setting prevents certain operations from executing as expected.
Solutions
4 solutions available1. Examine MongoDB Server Logs for Specific Details easy
Error 96 is generic; server logs provide the root cause.
1
Locate the MongoDB server log file. The default location varies by OS, but common paths include `/var/log/mongodb/mongod.log` on Linux or within the MongoDB installation directory on Windows.
2
Tail the log file in real-time to capture the error as it occurs, or review recent entries for errors preceding or coinciding with Error 96.
tail -f /var/log/mongodb/mongod.log3
Search for other error messages, warnings, or exceptions that appear around the time of the Operation Failed message. These will often pinpoint the actual underlying issue (e.g., network problems, disk space, insufficient memory, data corruption, invalid query, authentication failure).
2. Verify Disk Space and File System Health medium
Running out of disk space or file system errors can cause generic operation failures.
1
Check the available disk space on the server where MongoDB is running, particularly on the partitions hosting the data directory and journal files.
df -h2
If disk space is low, free up space by removing unnecessary files or expanding the storage. Consider moving data files to a larger partition if feasible.
3
Run file system check utilities (e.g., `fsck` on Linux, `chkdsk` on Windows) to ensure the file system is not corrupted.
sudo fsck -y /dev/sdX # Replace /dev/sdX with your partition4
Ensure MongoDB has appropriate read/write permissions to its data and log directories.
3. Review MongoDB Configuration and Resource Utilization medium
Incorrect configuration or resource exhaustion can lead to this error.
1
Examine your `mongod.conf` (or `mongos.conf`) file for any recently changed or suspicious settings. Pay attention to memory limits, network settings, and storage configurations.
2
Monitor system resources (CPU, RAM, network I/O) during the operation that fails. High utilization can indicate resource contention.
top -c | grep mongod # On Linux3
Check MongoDB's wiredTiger cache size. If it's too small, MongoDB might be performing excessive disk reads, leading to performance issues and potential failures. Adjust `storage.wiredTiger.engineConfig.cacheSizeGB` in your configuration if necessary.
4
If running in a replica set or sharded cluster, ensure all nodes are healthy and communicating properly. Network issues between nodes can cause operations to fail.
4. Validate Data Integrity and Query Syntax advanced
Corrupted data or malformed queries can trigger generic errors.
1
If the error occurs during a specific operation (e.g., insert, update, query), try to isolate the problematic document or query. Examine the data being processed for any unexpected formats or values.
2
Use MongoDB's built-in tools to check for data corruption. For example, running `db.collection.validate()` can help identify issues within a collection.
db.myCollection.validate( { full: true } )3
Carefully review the query that triggers the error. Ensure all field names, operators, and values are correctly formatted and adhere to MongoDB's query syntax. Incorrect or overly complex queries can sometimes lead to generic failures.
4
If you suspect data corruption and have a recent backup, consider restoring the affected collection or database to a clean state.