Examine the command output (if available) and the daemon and reqlib debug logs for a more detailed message error.

See "Setting Media Manager debug logging to a higher level" in the NetBackup Logging Reference Guide.

Identify the robotic process: look at the robot type and at the robot host on the robotic request or the robot host field of the volume being operated on. Verify that the robotic process to use for robotic control is available and that it handles requests.

Identify the robot control host by checking the device configuration. Only one configured robot control host should exist for each TL8, TLD, and TLH robot. All volumes in the volume configuration should have a robot host that matches the configured robot control host.

Check the system log on the robot control host to see if the robotic process processes the requests when communications with it are attempted.