You try to configure the command switchport mode trunk on an interface. However, you see the error message Command rejected: An interface whose trunk encapsulation is Auto cannot be configured to trunk mode. What command will fix the issue?

The command will not complete because the interface is set to dynamic auto, which implies the trunk protocol will be negotiated. You cannot configure it with switchport mode trunk until you statically set the encapsulation via the command switchport trunk encapsulation dot1q. The commands switchport mode trunk manual, no switchport mode dynamic auto, and no switchport trunk encapsulation auto are incorrect.