WARNING: Ignoring invalid value ‘share’ for parameter ‘security’

The value ‘share’ for paramater ‘security’ is no longer valid for recent versions of Samba, so if you were running an older version of Samba and then updated, you’ll probably getting these messages when trying to access as user ‘guest’ to a shared folder.

To fix this, replace:

security = share

with:

security = user
map to guest = Bad User