Warning: Attempt to read property "FldVar" on null (v8)

HiIm trying to upgrade my phpMaker version so it works with php version 8.When Im running php v8 Im getting loads of:
Warning: Attempt to read property “FldVar” on null in…If I switch back to running php v7 it all works.What could the issue be? I know the error is saying ‘FldVar’ is null, but how to fix?
Thanks

Make sure you have already enabled debug and checked also the HTTP response.

Thanks. I have error reporting enabled and have checked the HTTP Response. I cant see any obvious things. The Response in my debugger is the same as what I see on the page:

Warning: Attempt to read property “FldVar” on null in /home/sites/############### on line 730
Warning: Attempt to read property “FldDataType” on null in /home/sites/############### on line 785
Warning: Attempt to read property “FldDataType” on null in /home/sites/############### on line 787
Warning: Attempt to read property “FldDataType” on null in /home/sites/############### on line 785
etc…I think its connecting to the database fine, but for some reason is falling over at the line 730:function BuildSearchSql(&$Where, &$Fld, $MultiValue) {
$FldParm = substr($Fld->FldVar, 2);And line 785:function ConvertSearchValue(&$Fld, $FldVal) {
$Value = $FldVal;
if ($Fld->FldDataType == EW_DATATYPE_BOOLEAN) {Once I know why those lines arent working I can fix all the other (lines 787, 785 etc…)What do you think?

Not sure about it.