RB750r3 error

After entering a configuration script I get this error message so I immediately interrupted the power from the router.
This is the script.

/interface ethernet
set [ find default-name=ether2 ] master-port=ether1 name=\
    ether2-mirror-input
set [ find default-name=ether3 ] master-port=ether1
set [ find default-name=ether4 ] master-port=ether1
set [ find default-name=ether5 ] master-port=ether1 name=\
    ether5-mirror-output
/interface ethernet switch
set 0 mirror-source=ether2-mirror-input mirror-target=\
    ether5-mirror-output
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip hotspot profile
set [ find default=yes ] html-directory=flash/hotspot
/system routerboard settings
# Warning: memory not running at default frequency
set memory-frequency=1200DDR

The configuration script comes from the same router board.
RouterOs = 6.39.3
Firmware = 3.41
What is going on

This is false error message started few versions ago and partially corrected in recent version. Looks like still not fully corrected. I saw that on 750Gr3 too and successfully ignored…

Hello Jarda, tnx for your quicq reply.
The double post is a accedent sorry for this.