Hi Dungnh,
Could you try login with root and check?
{master:0}
root@Aa01_SW1_QFX_100010> show version | match "Junos:"
Junos: 14.1X53-D34
{master:0}
root@Aa01_SW1_QFX_100010> show version | match Model
Model: qfx5100-48t-6q
{master:0}
root@Aa01_SW1_QFX_100010> configure
Entering configuration mode
Try to type in the full command:
{master:0}[edit]
root@Aa01_SW1_QFX_100010# set protocols l2-learning decapsulate-accept-inner-vlan
{master:0}[edit]
root@Aa01_SW1_QFX_100010# show | compare
[edit protocols]
+ l2-learning {
+ decapsulate-accept-inner-vlan;
+ }