I've installed "Magisk-v17.0" with this method:
a) (re)installation "MagiskManager-v5.9.1(139).apk"
b) from Magisk Manager download "Magisk-v17.0.zip" on folder "Download"
c) on folder "Download" copy "Magisk-uninstaller-20180901.zip" (for any problems...)
d) reboot on recory mode
c) from...