Prevent copy and paste invalid data for data validation cells

That is the weakness of data validation - it is the same as any other cell. You can paste anything into the cell.

You could use VBA to prevent the user copying and pasting into data validation cells
(I assume you want the user to be able to use copy and paste in other cells)

You are repeating what you have already told us.

Do you want the user to be able to use copy and paste in other cells?

If you allow paste on cells with data validation but without dropdown, then Excel overwrites data validation
- do any of the cells have data validation without a dropdown?

Edit:
Just a thought ..
- are data validation cells in specific columns (without other data)?
- may be simpler to block paste in those specific columns

Thank you for the workbook - I will look at it tomorrow

test in attached workbook
data validation is in "yellow" cells

this code prevents: user selecting E4:F4 \ {CTRL} c \ click on B4 \ {CTRL} v
it does not prevent: user selecting E4:F4 \ {CTRL} c \ click on A4 \ {CTRL} v
I will try find a simple solution for that

in sheet module:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    On Error Resume Next
    Dim sel As Range, dv As Range, c As Integer
    Set dv = Me.Cells.SpecialCells(xlCellTypeAllValidation)
    Set sel = Selection
    c = 0
    c = Intersect(dv, sel).Cells.Count
    If c > 0 Then Application.CutCopyMode = False
End Sub

But, in here, it can be copied the text and paste it to the selected cell.

It means, when I copied only text and it can be pasted into selected cell.

Try more comprehensive solution in attached file

Thanks to @xladept and @sintek for their suggestions - see this thread


ThisWorkbook module:

Private Sub Workbook_Open()
    Call SetKey
    Application.EnableEvents = True
End Sub

SheetModule:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    On Error Resume Next
    With Application
        .EnableEvents = False
                If OverLap(Selection.Cells(1, 1)) > 0 Then .CutCopyMode = False
        .EnableEvents = True
    End With
End Sub

General Module:

Option Explicit
Public r As Long, c As Long
Public MyCount As Integer, CCM As Boolean, Ants As Range
Public PR As Range, DV As Range

Sub c_Macro()
'
' c_Macro Macro
' Get selection Address
'
' Keyboard Shortcut: Ctrl+c
'
    Selection.Copy
    MarchingAnts
End Sub

Sub SetKey()
'If key is Uppercase use Ctrl+Shift+Key but always use Ctrl
    Application.MacroOptions Macro:="c_Macro", ShortcutKey:="c"
End Sub

Sub MarchingAnts()
    On Error Resume Next
    CCM = Application.CutCopyMode
    If CCM <> True Then MyCount = 0 Else MyCount = MyCount + 1
    Select Case MyCount
        Case Is = 0:        Set Ants = Nothing
        Case Is > 0:        Set Ants = Selection
    End Select
End Sub

Function OverLap(rng As Range) As Integer
    On Error Resume Next
        If MyCount = 0 Then Exit Function
        r = Ants.Rows.Count: c = Ants.Columns.Count
        
        Set PR = rng.Resize(r, c)
        Set DV = rng.Parent.Cells.SpecialCells(xlCellTypeAllValidation)
        OverLap = Intersect(PR, DV).Cells.Count
End Function