Error: You cannot use this command on protected sheet

Sub Protect_All_Formula_cells()

Application.ScreenUpdating = False

For i = 1 To Sheets.Count

    With Sheets(i)
      .Unprotect Password:="abcd"
    
        With .Cells
         .Locked = False
         .FormulaHidden = False
        End With
        
         Cells.SpecialCells(xlCellTypeFormulas, 23).Select 'error line: you cannot use this command on protected sheet
         Selection.Locked = True
         Selection.FormulaHidden = False
        
Range("A1").Select
        
    .Protect Password:="abcd", DrawingObjects:=True, Contents:=True, Scenarios:=True, _
    AllowFormattingCells:=True, AllowFormattingColumns:=True, AllowFormattingRows:=True, _
    AllowInsertingHyperlinks:=True, AllowFiltering:=True
    
    End With
        
  Next i
  
Application.ScreenUpdating = True

End Sub

I have tried unprotecting the sheet with the code but still getting the error.

Solution??

The codeline where error occurs is not the one unprotected but the active sheet as you forgot the dot before Cells statement ‼

After inserting dot before cells statement, it gives error that select method of range class failed.

You cannot select cells on an inactive sheet.
Try

With .Cells.SpecialCells(xlCellTypeFormulas, 23)
   .Locked = True
   .FormulaHidden = False
End With

Solved!! Thanks a lot!

You're welcome & thanks for the feedback