The LX Array error message comes from errors induced in older databases.
You may therefore encounter this message if you are still on an older version of Heredis (prior to Heredis 2017) or when converting an old file to a new version of Heredis.
Heredis 2015 and all previous versions used a different proprietary database system to the one we have implemented from Heredis 2017. This system has been abandoned in part because it was unable to correct errors of this type.
These old databases cannot be restored. You need to start from a copy of your file or from a GEDCOM file predating the message.