My code has just recently stopped worked breaking with an "Object variable or With block variable not set." at the line in red.

With ws_target
    Debug.Print ws_target.Name
    For rr = 2 To 365 'days in post staff target worksheet
    tdate = .Cells(rr, 2)
    Set ref_date = ws_schedule.Columns(1).Find(tdate)
    ref_date_row = ref_date.Row
     Debug.Print ref_date_row
     ...
My guess is the 'set ref_date' reference has failed. But I have no idea why?

tdate = 1/3/2019
ws_target is a recognized worksheet
ws_schedule is also a recognized worksheet referring to a worksheet in a second open workbook
Column B, row 2 holds the date 1/3/2019, although formatted as ddd dd-mm.
red_date is defined as a range

Is anyone able to offer some support?