We have a custom program developed that connects to the sage file and our ERP, and pushed the invoices into Sage. (C#)
Everything worked prior with 2022.3 SDK. Recently upgraded the software on all machines to Sage 2023.0, and had to install the SDK for our transfer tool.

I had to install .NET 4.8, and upgraded the application to be using that framework as well.

Now I am getting this error when trying to open the sage file.

"System.MissingMethodException: 'Method not found: 'System.String Sage.Simply.Work.Repository.get_Func31()'.'"

 try
{
if (SDKInstanceManager.Instance.OpenDatabase(saifile, username, userpassword, true, "ww experiment", "SASDK", 1)) {
MessageBox.Show("Connection Success");
}
else { MessageBox.Show("Connection Failed"); }
}
catch (SDKException se) { MessageBox.Show(se.Message); }
catch (Exception sageEx) { MessageBox.Show(sageEx.Message); }
finally {
SDKInstanceManager.Instance.CloseDatabase();
}

It is failing on the IF statement and pops up with the above error.

I have cleared the BIN, and all references to SAGE SDK, reinstalled the SDK and added the references again, (because I found a post about a rouge DLL lingering)

Any advice?