Can't use f.lux or Night Shift. How can I work around this?
(Taken from user bobzippymail on a flux forum page)

delete &quot;backgrounditems.btm&quot; file under this path, and then restart your mac.
/Users/$your_user/Library/Application Support/com.apple.backgroundtaskmanagementagent/backgrounditems.btm

I would recommend making a duplicate of the file in case something goes wrong.