Error
Error Code:
186
MongoDB Error 186: Prohibits Client Metadata Changes
Description
Error 186, 'Client Metadata Cannot Be Mutated,' indicates an attempt to change critical client-side identification information after a connection has been established. This metadata, including application name and driver details, is typically set once during the initial connection handshake. Subsequent attempts to alter these immutable fields will trigger this error.
Error Message
Client Metadata Cannot Be Mutated
Known Causes
3 known causesAttempted Metadata Re-assignment
A client application or driver tried to set client metadata fields (e.g., `appName`) on a `MongoClient` instance or connection that has already been initialized.
Driver or ORM Misconfiguration
The client driver, ORM, or an underlying library is configured to modify connection details after the initial handshake, which includes immutable client metadata.
Incompatible Driver Version
Using an outdated or non-standard MongoDB driver that has a bug or an incorrect implementation regarding client metadata handling.
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