Dell OS S4148F Error: Interface is not in default mode

I tried associating an VLAN interface to the non-default VRF that you created, however, the configuration failed with % Error: Interface is not in default mode

# show ip vrf public_cust
VRF-Name Interfaces
public_cust

# show vlan 4001

Codes: * - Default VLAN, M - Management VLAN, R - Remote Port Mirroring VLANs,
@ - Attached to Virtual Network, P - Primary, C - Community, I - Isolated
Q: A - Access (Untagged), T - Tagged
NUM Status Description Q Ports
4001 Active T Eth1/1/50

# show running-configuration interface vlan 4001
!
interface vlan4001
mode L3
shutdown
mtu 9216
ip address 169.254.255.253/31
no ip igmp snooping
no ipv6 mld snooping

# configure terminal
(config)# interface vlan 4001
(conf-if-vl-4001)# ip vrf forwarding public_cust
% Error: Interface is not in default mode

I couldn't find any information regarding this error and what it means. Any help will be appreciated.