MS Access 2016 .Net Framework Reference

Problems with MS Access Reference(s) after changing from a server with 2008 R2 to 2012 R2 (and a new install of Access 2016)
The following code is what has initially highlighted the issue.

Public Function fSHA256Base64(s As String, k As String) As String
      Dim lngLoop                   As Long
      Dim oUTF, oEnc
      Dim hmac()                    As Byte
      Dim strText                   As String
      Dim strTemp                   As String

12890 strText = s
12900 Set oUTF = CreateObject("System.Text.UTF8Encoding")
12910 Set oEnc = CreateObject("System.Security.Cryptography.HMACSHA256")

12920 oEnc.Key = oUTF.GetBytes_4(k)
12930 hmac = oEnc.ComputeHash_2(oUTF.GetBytes_4(s))
12940 strTemp = Base64Encode(hmac())
12950 fSHA256Base64 = strTemp
End Function

Line 12900 throws run time error -2146232576 (80131700) ‘Automation Error’.

SVR with 2008R2 had referenced System.tlb from the v2.0.50727 .Net Framework folder.
SVR with 2012R2 has referenced from the v4.0.30319 folder.


However, when I change new server from v4 to the v2 file, even though it appears to have changed it (judging by the 'Location' reference), the next time I open the Reference panel it has changed back to v4! This happens even on a new file where the .net wasn’t even referenced to begin with. Ie I add system.tlb from the v2 folder. When I next open references the ref location is the v4 folder!


1)      Have I correctly identified the .net version as the cause of the actual error?
2)      How can I force the reference to the older version / stop it changing itself?

Many thanks