What does Windows error code 7066 (ERROR_CTX_CDM_CONNECT) mean?

ERROR_CTX_CDM_CONNECT

The Client Drive Mapping Service Has Connected on Terminal Connection.

ERROR_CTX_CDM_CONNECT is Win32 error 7066 (0x00001B9A).

What to verify

Verify whether the drive-mapping virtual channel is connected and its state is interpreted as a notification rather than a failure. Check session ID and user, client name and protocol, and effective drive-redirection policy.

Likely causes

• a user session enables client drive redirection.
• the RDP virtual channel is established after logon.
• policy permits device redirection.
• a reconnect restores the client drive mapping channel.

Troubleshooting steps

1. Collect session ID and user.
2. Record client name and protocol.
3. Correlate effective drive-redirection policy with TerminalServices operational logs, session and user-configuration records, device or modem diagnostics, and the caller’s connection trace.

Handling, retry, and recovery

Treat the value as a state transition, enumerate the resulting mappings, and report an error only if the expected devices fail to appear.

Related errors

ERROR_CTX_CDM_DISCONNECT reports the opposite channel transition

Example

A monitoring component receives this value during session logon. It records the channel connection and then verifies which client drives were actually published.

References

• Microsoft: Win32 system error range containing this code
• Microsoft: Remote Desktop Services API
• Microsoft: WTS configuration classes
• Microsoft: WTSAPI32 reference