We are seeing the same issue. deDel has been depreciated since Asterisk 1.4 and has now been removed from Asterisk.
Per documentation the replacement is DB_DELETE. the syntax is different.
Edit: /etc/asterisk/extensions_override_fop2.conf
Around line 192 and 267 replace dbDel with DB_DELETE.
192: exten => *79,n,Noop(${DB_DELETE(fop2state/${CHAN})})
267: exten => *76,n,Noop(${DB_DELETE(fop2state/${CHAN})})
Gary Herbstman
For additional details see this KB: https://www.bytesolutions.com/asterisk-freepbx-fop2-error-disabling-do-not-disturb-dnd/