Changing settings for checkbox "Blank the physical screen..." and "Disable the shading effect..." in the server UI  is ineffective after upgrading from repositories to v8.6.

Problem is triggered by the fact that EnableScreenBlankingEffect key in node.cfg is wrongly renamed into EnableScreenBlanking by the automatic upgrade procedure. As a result,  EnableScreenBlanking is duplicated and EnableScreenBlankingEffect is missing. 

This happens only when the EnableScreenBlankingEffect is not commented (the hash # character doesn't pre-pend the key name).

Upgrading by using the appropriate NoMachine package for Windows is not affected.

To fix the problem manually, edit node.cfg and rename the duplicated entry in order to have EnableScreenBlankingEffect instead of EnableScreenBlanking :

#
# Enable or disable the screen shading effect when there is someone
# connected to the physical display and the screen is blanked.
#
# 1: Enabled. Enable the screen shading effect fading from black
#    to different levels of gray.
#
# 0: Disabled. Disable the screen shading effect.
#
EnableScreenBlankingEffect 1