Prevent enter to move to the next cell if no character is typed

[Aussiebear]

Private requiredCellAddressesArray As Variant 
' Declare at the top of the module

Private Sub Worksheet_Activate()
    ' This event fires when the sheet becomes active.
    ' It's a good place to initialize our array of cell addresses once.
    If IsEmpty(requiredCellAddressesArray) Then 
        ' Only initialize if not already done
        Call InitializeRequiredCellsArray
    End If
    ' Optional: Ensure the first cell in the sequence is activated when the sheet is activated
    If Not IsEmpty(requiredCellAddressesArray) Then
        Me.Range(requiredCellAddressesArray(LBound(requiredCellAddressesArray))).Activate
    End If
End Sub

Private Sub InitializeRequiredCellsArray()
    ' Define your non-contiguous cells in the exact "snake game" order.
    ' Ensure the order is precise as this defines the user's path.
    requiredCellAddressesArray = Array("B4", "B5", "B6", "B7", "B8", "B9", "B10", "B11", "B12", "B13", "B14", "B15", "B16", "C16", "D16", _
    "E16", "F16", "G16", "G15", "G14", "G13", "G12", "G11", "F11", "E11", "E10", "E9", "E8", "F8", "G8", "H8", "I8", "J8", "J9", "J10", "J11", _
    "J12", "J13", "K13", "L13", "M13", "N13", "N12", "N11", "N10", "O10", "P10", "Q10", "Q9", "Q8", "R8", "S8", "S7", "S6", "S5", "R5", "Q5", _
    "P5", "O5", "N5", "M5", "M4", "L4", "K4", "J4", "I4", "I5", "H5", "G5", "F5", "F4", "F3", "G3", "G2", "H2", "I2", "J2", "K2", "L2", "M2", "N2", _
    "O2", "P2", "Q2", "R2", "R3", "S3", "T3", "U3", "V3", "V4", "V5", "V6", "V7", "V8", "V9", "W9", "X9", "X8", "X7", "Y7", "Y6", "Y5", "Y4", "X4", _
    "X3", "X2", "Y2", "Z2", "AA2", "AA3", "AA4", "AA5", "AA6", "AA7", "AA8", "AA9", "AA10", "Z10", "Z11", "Z12", "Z13", "Z14", "Z15", "Y15", "X15", _
    "W15", "V15", "U15", "U16", "T16", "S16", "R16", "Q16", "P16", "O16", "N16", "M16")
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim currentCellAddress As String
    Dim previousCellAddressInSequence As String 
    ' Renamed for clarity
    Dim currentCellIndexInArray As Long 
    ' Renamed for clarity
    Dim i As Long
    Dim blnTargetIsInRequiredPath As Boolean
    Dim rngPreviousCell As Range 
    ' To hold the actual Range object of the previous cell
    ' Turn off events to prevent re-triggering this macro during our own actions
    Application.EnableEvents = False
    On Error GoTo CleanUp
    If IsEmpty(requiredCellAddressesArray) Then 
        ' Ensure array is initialized
        Call InitializeRequiredCellsArray
    End If
    ' 1. Determine if the selected cell (Target) is part of our required path
    blnTargetIsInRequiredPath = False
    currentCellIndexInArray = -1 
    ' Initialize to not found
    For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
        ' Compare the full address to ensure exact match (e.g., $A$1 vs $A$1)
        If Target.Address = Me.Range(requiredCellAddressesArray(i)).Address Then
            currentCellIndexInArray = i
            blnTargetIsInRequiredPath = True
            Exit For
        End If
    Next i
    ' 2. Handle invalid selections (multi-cell or outside the path) 
    If Not blnTargetIsInRequiredPath Or Target.Cells.Count > 1 Then
        Dim firstEmptyRequiredCell As Range 
        ' Holds the Range object of the first empty cell
        firstEmptyRequiredCellIndex = -1
        ' Find the first empty cell in the defined sequence
        For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
            Set firstEmptyRequiredCell = Me.Range(requiredCellAddressesArray(i))
            If IsEmpty(firstEmptyRequiredCell.Value) Or Trim(firstEmptyRequiredCell.Value) = "" Then
                firstEmptyRequiredCellIndex = i
                Exit For
            End If
        Next i
        ' If there's an empty required cell, activate it and warn the user
        If firstEmptyRequiredCellIndex <> -1 Then
            MsgBox "Please fill in all preceding mandatory fields. Cell " & firstEmptyRequiredCell.Address(False, False) & " is blank.", vbExclamation, "Mandatory Field"
            firstEmptyRequiredCell.Activate
        Else
            ' All required cells are filled, allow movement freely outside the path.
            ' No action needed, user can move elsewhere.
        End If
        ' 3. Handle valid single cell selection within the required path 
    Else 
        ' User selected a designated single cell in the sequence
        ' Check if the immediately preceding cell IN THE SEQUENCE is filled
        If currentCellIndexInArray > LBound(requiredCellAddressesArray) Then
            ' Get the address of the actual previous cell in the defined sequence
            previousCellAddressInSequence = requiredCellAddressesArray(currentCellIndexInArray - 1)
            Set rngPreviousCell = Me.Range(previousCellAddressInSequence)
            ' Check if that specific previous cell is empty
            If IsEmpty(rngPreviousCell.Value) Or Trim(rngPreviousCell.Value) = "" Then
                MsgBox "Please fill in cell " & rngPreviousCell.Address(False, False) & " before moving to " & Target.Address(False, False) & ".", vbExclamation, "Mandatory Field"
                rngPreviousCell.Activate 
                ' Force user back to the unfilled previous cell
            End If
        End If
        ' Additionally, ensure no cells earlier in the sequence were skipped
        ' This catches cases where they fill the immediate previous, but skipped one even earlier.
        For i = LBound(requiredCellAddressesArray) To currentCellIndexInArray - 1
            Set currentCell = Me.Range(requiredCellAddressesArray(i)) 
            ' Using currentCell to iterate through preceding
            If IsEmpty(currentCell.Value) Or Trim(currentCell.Value) = "" Then
                MsgBox "Please fill in all preceding mandatory fields. Cell " & currentCell.Address(False, False) & " is blank.", vbExclamation, "Mandatory Field"
                currentCell.Activate 
                ' Go back to the first skipped cell
                Exit For 
                ' Stop checking once the first skipped cell is found
            End If
        Next i
    End If
    CleanUp:    
    Application.EnableEvents = True
    If Err.Number <> 0 Then
        MsgBox "An error occurred: " & Err.Description, vbCritical, "Error"
    End If
End Sub

[Aussiebear]

aarrrggh!!! Final effort for me with this code

Private requiredCellAddressesArray As Variant 
' Stores the sequence of cell addresses
Private expectedCharsArray As Variant 
      ' Stores the expected character for each cell in the sequence
' Flag to ensure initialization only happens once
Private isInitialized As Boolean

Private Sub Worksheet_Activate()
    ' This event fires when the sheet becomes active.
    ' It's a good place to initialize our arrays once.
    If Not isInitialized Then
        Call InitializeRequiredCellsArray        isInitialized = True
    End If
    ' Ensure the first cell in the sequence is activated when the sheet is activated
    If Not IsEmpty(requiredCellAddressesArray) Then
        ' Optional: Clear content of all cells in the sequence on activate, if needed
        ' For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
            '     Me.Range(requiredCellAddressesArray(i)).ClearContents
        ' Next i
        Me.Range(requiredCellAddressesArray(LBound(requiredCellAddressesArray))).Activate
    End If
End Sub

Private Sub InitializeRequiredCellsArray() 
    ' Renamed from InitializeRoute for consistency with previous discussion
    ' Define your non-contiguous cells in the exact "snake game" order.
    requiredCellAddressesArray = Array("B4", "B5", "B6", "B7", "B8", "B9", "B10", "B11", "B12", "B13", "B14", "B15", "B16", "C16", "D16", "E16", "F16", "G16", "G15", _
    "G14", "G13", "G12", "G11", "F11", "E11", "E10", "E9", "E8", _        "F8", "G8", "H8", "I8", "J8", "J9", "J10", "J11", "J12", "J13", "K13", "L13", "M13", "N13", "N12", "N11", _
    "N10", "O10", "P10", "Q10", "Q9", "Q8", "R8", "S8", "S7", "S6", "S5", "R5", "Q5", "P5", "O5", "N5", "M5", "M4", "L4", "K4", "J4", "I4", "I5", "H5", "G5", "F5", "F4", "F3", _
    "G3", "G2", "H2", "I2", "J2", "K2", "L2", "M2", "N2", "O2", "P2", "Q2", "R2", "R3", "S3", "T3", "U3", "V3", "V4", "V5", "V6", "V7", "V8", "V9", "W9", "X9", "X8", "X7", "Y7", _
    "Y6", "Y5", "Y4", "X4", "X3", "X2", "Y2", "Z2", "AA2", "AA3", "AA4", "AA5", "AA6", "AA7", "AA8", "AA9", "AA10", "Z10", "Z11", "Z12", "Z13", "Z14", "Z15", "Y15", "X15", _
    "W15", "V15", "U15", "U16", "T16", "S16", "R16", "Q16", "P16", "O16", "N16", "M16")
    ' Define the expected characters for each cell in the exact same order as requiredCellAddressesArray
    expectedCharsArray = Array("8", "C", "r", "f", "e", """", "P", "N", "K", ";", "T", "_", "\", ".", "&", ">", "A", "b", "[", "!", "x", "r", ";", "3", "V", "3", "x", "j", "&", "C", "Z", "n", _
    """", "z", "$", "i", "\", "w", "%", "N", "d", "H", "f", "Z", "H", "x", "E", "M", "V", "#", "V", "F", "3", "B", "q", "B", """", ":", "1", "v", "A", "y", "Q", "c", ":", "G", "c", "g", "K", _
    "<", "{", "8", "g", "8", "g", "G", ":", "c", "Q", "y", "C", "2", "{", "K", "j", "K", "j", "B", "v", ";", "j", "Q", ";", "X", "L", "3", "#", "0", "@", "X", "@", "<", "}", "7", "j", "7", ".", _
    "7", "[", "|", "[", "m", "}", "<", "M", "A", "F", "h", "F", ".", "L", "$", "w", "<", "D", "2", ".", ",", "w", "Q", "1", "a", "k", "i", "n", "a", "D", "%")
    ' Verify both arrays have the same length
    If UBound(requiredCellAddressesArray) <> UBound(expectedCharsArray) Then
        MsgBox "Error: The list of required cells and expected characters do not match in length. Please check the VBA code.", vbCritical, "Initialization Error"
        ' Optionally, reset isInitialized to False or disable events to prevent further errors
        isInitialized = False
        Exit Sub
    End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim currentCellAddress As String
    Dim previousCellAddressInSequence As String
    Dim currentCellIndexInArray As Long
    Dim i As Long
    Dim blnTargetIsInRequiredPath As Boolean
    Dim rngPreviousCell As Range
    Dim rngCurrentCellInLoop As Range 
    ' For iterating through preceding cells
    ' Turn off events to prevent re-triggering this macro during our own actions
    Application.EnableEvents = False
    On Error GoTo CleanUp
    ' Ensure arrays are initialized (especially if user opens directly to this sheet without activate)
    If Not isInitialized Then
        Call InitializeRequiredCellsArray        isInitialized = True
        If UBound(requiredCellAddressesArray) <> UBound(expectedCharsArray) Then 
            ' Check again in case of error in init
            Application.EnableEvents = True
            Exit Sub '
            Exit if arrays are mismatched
        End If
    End If
    ' 1. Determine if the selected cell (Target) is part of our required path 
    blnTargetIsInRequiredPath = False
    currentCellIndexInArray = -1 
    ' Initialize to not found
    For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
        If Target.Address = Me.Range(requiredCellAddressesArray(i)).Address Then
            currentCellIndexInArray = i
            blnTargetIsInRequiredPath = True
            Exit For
        End If
    Next i
    ' 2. Handle invalid selections (multi-cell or outside the path) 
    If Not blnTargetIsInRequiredPath Or Target.Cells.Count > 1 Then
        Dim firstEmptyOrIncorrectRequiredCell As Range 
        ' Holds the Range object of the first problematic cell
        firstProblematicCellIndex = -1
        ' Find the first empty or incorrect cell in the defined sequence
        For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
            Set firstEmptyOrIncorrectRequiredCell = Me.Range(requiredCellAddressesArray(i))
            ' Check for empty OR incorrect character
            If IsEmpty(firstEmptyOrIncorrectRequiredCell.Value) Or Trim(firstEmptyOrIncorrectRequiredCell.Value) = "" _
                Or CStr(firstEmptyOrIncorrectRequiredCell.Value) <> expectedCharsArray(i) Then 
                ' CStr to ensure type compatibility
                firstProblematicCellIndex = i
                Exit For
            End If
        Next i
        ' If there's a problematic required cell, activate it and warn the user
        If firstProblematicCellIndex <> -1 Then
            MsgBox "Please fill in all preceding mandatory fields correctly. Cell " & firstEmptyOrIncorrectRequiredCell.Address(False, False) & _
            " is either blank or contains an incorrect character." & "Expected: '" & expectedCharsArray(firstProblematicCellIndex) & "'", vbExclamation, "Mandatory Field / Incorrect Character"
            firstEmptyOrIncorrectRequiredCell.Activate
        Else
            ' All required cells are filled and correct, allow movement freely outside the path.
            ' No action needed, user can move elsewhere.
        End If
        ' 3. Handle valid single cell selection within the required path
    Else 
        ' User selected a designated single cell in the sequence
        ' Check if the immediately preceding cell IN THE SEQUENCE is filled and correct
        If currentCellIndexInArray > LBound(requiredCellAddressesArray) Then
            previousCellAddressInSequence = requiredCellAddressesArray(currentCellIndexInArray - 1)
            Set rngPreviousCell = Me.Range(previousCellAddressInSequence)
            ' Check if that specific previous cell is empty OR contains the wrong character
            If IsEmpty(rngPreviousCell.Value) Or Trim(rngPreviousCell.Value) = "" Or CStr(rngPreviousCell.Value) <> expectedCharsArray(currentCellIndexInArray - 1) Then
                MsgBox "Please fill in cell " & rngPreviousCell.Address(False, False) & " correctly before moving to " & Target.Address(False, False) & ". Expected: '" & _
                expectedCharsArray(currentCellIndexInArray - 1) & "'", vbExclamation, "Mandatory Field / Incorrect Character"
                rngPreviousCell.Activate 
                ' Force user back to the unfilled/incorrect previous cell
            End If
        End If
        ' Additionally, ensure no cells earlier in the sequence were skipped AND are correct
        For i = LBound(requiredCellAddressesArray) To currentCellIndexInArray - 1
            Set rngCurrentCellInLoop = Me.Range(requiredCellAddressesArray(i))
            If IsEmpty(rngCurrentCellInLoop.Value) Or Trim(rngCurrentCellInLoop.Value) = "" Or CStr(rngCurrentCellInLoop.Value) <> expectedCharsArray(i) Then
                MsgBox "Please fill in all preceding mandatory fields correctly. Cell " & rngCurrentCellInLoop.Address(False, False) & " is either blank or contains an incorrect character. " & _
                "Expected: '" & expectedCharsArray(i) & "'", vbExclamation, "Mandatory Field / Incorrect Character"
                rngCurrentCellInLoop.Activate 
                ' Go back to the first skipped/incorrect cell
                Exit For 
                ' Stop checking once the first problematic cell is found
            End If
        Next i
    End If
    CleanUp:
    Application.EnableEvents = True
    If Err.Number <> 0 Then
        MsgBox "An error occurred: " & Err.Description & vbCrLf & "Error Number: " & Err.Number, vbCritical, "Error"
    End If
End Sub

[vanhunk]

@Aussiebear: Thank you so much for all your effort.

Your code came very close to achieve the required result. It is sort of working.

Let me explain:
Going down, the code works as expected.
Going right or left, the cursor leaves the path (route), complains unnecessarily and jumps to the next block (cell) in the path.
Going up, it takes a detour, all the way down, until it leaves the path, complains unnecessarily, and then jumps to the next block in the both.


Without the detours, and complaining where it shouldn't, it does follow the path and does catch blanks and incorrect inputs.

Kind Regards
vanhunk

[vanhunk]

I have added the latest version by Aussiebear

[Aussiebear]

Private requiredCellAddressesArray As Variant 
' Stores the sequence of cell addresses
Private expectedCharsArray As Variant 
      ' Stores the expected character for each cell in the sequence
' Flag to ensure initialization only happens once
Private isInitialized As Boolean

Private Sub Worksheet_Activate()
    ' This event fires when the sheet becomes active.
    ' It's a good place to initialize our arrays once.
    If Not isInitialized Then
        Call InitializeRequiredCellsArray
        isInitialized = True
    End If
    ' Ensure the first cell in the sequence is activated when the sheet is activated
    If Not IsEmpty(requiredCellAddressesArray) Then
        ' Optional: Clear content of all cells in the sequence on activate, if needed
        ' For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
        '     Me.Range(requiredCellAddressesArray(i)).ClearContents
    ' Next i
    ' Find the first empty or incorrect cell to activate initially
    Dim firstProblematicCellToActivate As Range
    Dim idx As Long
    For idx = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
        Set firstProblematicCellToActivate = Me.Range(requiredCellAddressesArray(idx))
            If IsEmpty(firstProblematicCellToActivate.Value) Or Trim(firstProblematicCellToActivate.Value) = "" Or _
                CStr(firstProblematicCellToActivate.Value) <> expectedCharsArray(idx) Then               
                firstProblematicCellToActivate.Activate
                Exit For
            ElseIf 
                idx = UBound(requiredCellAddressesArray) Then 
                ' If all are filled, activate the last one                Me.Range(requiredCellAddressesArray(UBound(requiredCellAddressesArray))).Activate
            End If
        Next idx
    End If
End Sub

Private Sub InitializeRequiredCellsArray()
    ' Define your non-contiguous cells in the exact "snake game" order.
    requiredCellAddressesArray = Array("B4", "B5", "B6", "B7", "B8", "B9", "B10", "B11", "B12", "B13", "B14", "B15", "B16", "C16", "D16", "E16", "F16", "G16", "G15", _
    "G14", "G13", "G12", "G11", "F11", "E11", "E10", "E9", "E8", "F8", "G8", "H8", "I8", "J8", "J9", "J10", "J11", "J12", "J13", "K13", "L13", "M13", "N13", "N12", "N11", _
    "N10", "O10", "P10", "Q10", "Q9", "Q8", "R8", "S8", "S7", "S6", "S5", "R5", "Q5", "P5", "O5", "N5", "M5", "M4", "L4", "K4", "J4", "I4", "I5", "H5", "G5", "F5", "F4", _
    "F3", "G3", "G2", "H2", "I2", "J2", "K2", "L2", "M2", "N2", "O2", "P2", "Q2", "R2", "R3", "S3", "T3", "U3", "V3", "V4", "V5", "V6", "V7", "V8", "V9", "W9", "X9", "X8", _
    "X7", "Y7", "Y6", "Y5", "Y4", "X4", "X3", "X2", "Y2", "Z2", "AA2", "AA3", "AA4", "AA5", "AA6", "AA7", "AA8", "AA9", "AA10", "Z10", "Z11", "Z12", "Z13", "Z14", "Z15", _
    "Y15", "X15", "W15", "V15", "U15", "U16", "T16", "S16", "R16", "Q16", "P16", "O16", "N16", "M16")
    ' Define the expected characters for each cell in the exact same order as requiredCellAddressesArray
    expectedCharsArray = Array("8", "C", "r", "f", "e", """", "P", "N", "K", ";", "T", "_", "\", ".", "&", ">", "A", "b", "[", "!", "x", "r", ";", "3", "V", "3", "x", "j", "&", "C", "Z", _
    "n", """", "z", "$", "i", "\", "w", "%", "N", "d", "H", "f", "Z", "H", "x", "E", "M", "V", "#", "V", "F", "3", "B", "q", "B", """", ":", "1", "v", "A", "y", "Q", "c", ":", "G", "c", "g", _
    "K", "<", "{", "8", "g", "8", "g", "G", ":", "c", "Q", "y", "C", "2", "{", "K", "j", "K", "j", "B", "v", ";", "j", "Q", ";", "X", "L", "3", "#", "0", "@", "X", "@", "<", "}", "7", "j", _
    "7", ".", "7", "[", "|", "[", "m", "}", "<", "M", "A", "F", "h", "F", ".", "L", "$", "w", "<", "D", "2", ".", ",", "w", "Q", "1", "a", "k", "i", "n", "a", "D", "%")
    ' Verify both arrays have the same length
    If UBound(requiredCellAddressesArray) <> UBound(expectedCharsArray) Then
        MsgBox "Error: The list of required cells and expected characters do not match in length. Please check the VBA code.", vbCritical, "Initialization Error"
        isInitialized = False 
        ' Prevent further execution if there's a mismatch
        Exit Sub
    End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim currentCellAddress As String
    Dim previousCellAddressInSequence As String
    Dim currentCellIndexInArray As Long
    Dim i As Long
    Dim blnTargetIsInRequiredPath As Boolean
    Dim rngPreviousCell As Range
    Dim rngCurrentCellInLoop As Range 
    ' For iterating through preceding cells
    Dim targetIsPreviousCellInSequence As Boolean 
    ' New flag for specific case
    ' Turn off events to prevent re-triggering this macro during our own actions
    Application.EnableEvents = False
    On Error GoTo CleanUp
    ' Ensure arrays are initialized (especially if user opens directly to this sheet without activate)
    If Not isInitialized Then
        Call InitializeRequiredCellsArray
        isInitialized = True
        If UBound(requiredCellAddressesArray) <> UBound(expectedCharsArray) Then 
            ' Check again in case of error in init
            Application.EnableEvents = True
            Exit Sub 
            ' Exit if arrays are mismatched
        End If
    End If
    '  1. Determine if the selected cell (Target) is part of our required path
    blnTargetIsInRequiredPath = False
    currentCellIndexInArray = -1 
    ' Initialize to not found
    For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
        If Target.Address = Me.Range(requiredCellAddressesArray(i)).Address Then
            currentCellIndexInArray = i
            blnTargetIsInRequiredPath = True
            Exit For
        End If
    Next i
    '  2. Handle cases based on where the user clicked 
    ' Case 1: User clicked on a single cell within the designated path.
    If blnTargetIsInRequiredPath And Target.Cells.Count = 1 Then
        ' Check if the immediately preceding cell IN THE SEQUENCE is filled and correct
        ' This is the "snake game" logic.
        If currentCellIndexInArray > LBound(requiredCellAddressesArray) Then
            previousCellAddressInSequence = requiredCellAddressesArray(currentCellIndexInArray - 1)
            Set rngPreviousCell = Me.Range(previousCellAddressInSequence)
            ' Check if that specific previous cell is empty OR contains the wrong character
            If IsEmpty(rngPreviousCell.Value) Or Trim(rngPreviousCell.Value) = "" Or CStr(rngPreviousCell.Value) <> expectedCharsArray(currentCellIndexInArray - 1) Then
                MsgBox "Please fill in cell " & rngPreviousCell.Address(False, False) & " correctly before moving to " & Target.Address(False, False) & ". Expected: '" & _
                expectedCharsArray(currentCellIndexInArray - 1) & "'", vbExclamation, "Mandatory Field / Incorrect Character"
                rngPreviousCell.Activate 
                ' Force user back to the unfilled/incorrect previous cell
                GoTo CleanUp 
                ' Exit the sub after activating the correct cell
            End If
        End If
        ' Additionally, ensure no cells earlier in the sequence were skipped AND are correct
        ' This catches cases where they fill the immediate previous, but skipped one even earlier.
        For i = LBound(requiredCellAddressesArray) To currentCellIndexInArray - 1
            Set rngCurrentCellInLoop = Me.Range(requiredCellAddressesArray(i))
            If IsEmpty(rngCurrentCellInLoop.Value) Or Trim(rngCurrentCellInLoop.Value) = "" Or CStr(rngCurrentCellInLoop.Value) <> expectedCharsArray(i) Then
                MsgBox "Please fill in all preceding mandatory fields correctly. Cell " & rngCurrentCellInLoop.Address(False, False) & " is either blank or contains an incorrect character. " & _
                "Expected: '" & expectedCharsArray(i) & "'", vbExclamation, "Mandatory Field / Incorrect Character"
                rngCurrentCellInLoop.Activate 
                ' Go back to the first skipped/incorrect cell
                GoTo CleanUp 
                ' Exit the sub after activating the correct cell
            End If
        Next i
        ' Case 2: User clicked outside the designated path, or selected multiple cells.
    Else 
        ' Not blnTargetIsInRequiredPath Or Target.Cells.Count > 1
        Dim firstProblematicCellToActivate As Range
        Dim firstProblematicCellIndex As Long
        firstProblematicCellIndex = -1 
        ' Initialize to not found
        ' Find the first empty or incorrect cell in the ENTIRE defined sequence
        For i = LBound(requiredCellAddressesArray) To UBound(requiredCellAddressesArray)
            Set firstProblematicCellToActivate = Me.Range(requiredCellAddressesArray(i))
            If IsEmpty(firstProblematicCellToActivate.Value) Or Trim(firstProblematicCellToActivate.Value) = "" Or CStr(firstProblematicCellToActivate.Value) <> expectedCharsArray(i) Then
                firstProblematicCellIndex = i
                Exit For
            End If
        Next i
        ' If there's a problematic required cell, activate it and warn the user
        If firstProblematicCellIndex <> -1 Then
            MsgBox "Please complete all mandatory fields correctly before moving away or selecting multiple cells. Cell " & firstProblematicCellToActivate.Address(False, False) & _
            " is either blank or contains an incorrect character. " & "Expected: '" & expectedCharsArray(firstProblematicCellIndex) & "'", vbExclamation, _
            "Mandatory Field / Invalid Selection" 
            firstProblematicCellToActivate.Activate
            GoTo CleanUp 
            ' Exit the sub after activating the correct cell
        Else
            ' All required cells are filled and correct. User is allowed to move freely.
            ' No action needed, user can move elsewhere.
        End If
    End If
    CleanUp:    Application.EnableEvents = True
    If Err.Number <> 0 Then
        MsgBox "An error occurred: " & Err.Description & vbCrLf & "Error Number: " & Err.Number, vbCritical, "Error"
    End If
End Sub

[vanhunk]

Hi Aussiebear, thank you for sticking it out, unfortunately the behaviour has not changed from the previous post.
Regards
vanhunk

[Aussiebear]

Okay.... I going to have to admit defeat.