[Nokia 3]adb reboot bootloader failed

Question

I have Nokia 3 Android 7.1.1 connected to PC Windows 8.

Problem is:

C:\>adb reboot bootloader
reboot failed: -1

Reason to do it is to flash/root in future. Other commands ok:

C:\>adb devices -l
List of devices attached
NE1GAM0760502899       device product:TA-1032_00WW model:TA_1032 device:NE1 transport_id:11
C:\>adb reboot
[...really reboot as expected]
C:\>adb reboot recovery
[...really reboot to recovery]
C:\>adb --version
Android Debug Bridge version 1.0.39
Version 0.0.1-4500957
Installed as C:\Users\nobody\AppData\Local\Android\Sdk\platform-tools\adb.exe
C:\>adb -t 11 reboot bootloader
reboot failed: -1


C:\>adb shell getprop
...
[ro.build.date.utc]: [1511256803]
[ro.build.description]: [TA-1032_00WW-user 7.1.1 NMF26O 00WW_2_15H release-keys]
[ro.build.display.id]: [00WW_2_15H]
[ro.build.flavor]: [NE1_00WW_FIH-user]
[ro.build.host]: [NJ-SW-UBUNTU-S7]
[ro.build.id]: [NMF26O]
[ro.build.product]: [NE1]
[ro.build.tags]: [release-keys]
[ro.build.type]: [user]
[ro.build.user]: [foxconn2]
[ro.build.version.incremental]: [00WW_2_15H]
[ro.build.version.preview_sdk]: [0]
[ro.build.version.release]: [7.1.1]
[ro.build.version.sdk]: [25]
[ro.build.version.security_patch]: [2017-12-01]
...

What's wrong?

I can reboot to fastboot manually from recovery menu ok.