Is the file normally read-only? You could try writeresPassword:="myPassword") or take it even further and try ReadOnly:=False as well

No, it's not a read-only. It's a full access password. I can open it from the Windows interface, and enter the password at the prompt. When I open it with the code above, the spreadsheet interface prompts for the password, but won't open until the password is successfully entered (in other words, it doesn't "see" the password passed via the command line).

Yea, your's is the correct working syntax for a normal password excel file.

Did you try the writeres or readonly and see if it changed the behavior at all?

The only other thing I can think of right now is admin privileges on the machine maybe. Have you tried on other machines or other files? All do the same?

Tried moving to a different VM - same behavior. Looking at the parameters for Workbooks.Open, I found "WriteResPassword". Tried that; no change. Set ReadOnly:=False and IgnoreReadOnlyRecommended:=False. No joy. Then, I removed the password protection from the spreadsheet and re-saved it. Tried to open with:
Set wb2 = Workbooks.Open(FileName:="myFile.xlsm", password:="myPassword")
Now, spreadsheet doesn't open (can still open from Windows).
The reference I'm using is "Microsoft Excel 16.0 Object Library" - is that the correct reference? Is there a better library to use?
At this point, pretty much spinning my wheels.

Have you tried using Late Binding instead?

    Dim objExcel As Object, objWB As Object
    Dim myFilename As String, myPassword As String
    
    myFilename = "Path To Your Excel File"
    myPassword = "Your Password"

    Set objExcel = CreateObject("Excel.Application")
    Set objWB = objExcel.Workbooks.Open(Filename:=myFilename, Password:=myPassword)
    objExcel.Visible = True
    objExcel.WindowState = 3 '1-normal ; 2-minimized ; 3-maximized

    Set objWB = Nothing
    Set objExcel = Nothing

Kevin,

PERFECT! Works Great!  THANK YOU!