GenerateAppearances = true; System.NullReferenceException
After years of production, I just changed it from:
if (stamper.AcroFields != null)
{
f.GenerateAppearances = true;
foreach(var field in f.Fields)
{
f.SetField(field.Key, f.GetField(field.Key));
}
stamper.FormFlattening = true;
}
to
if (stamper.AcroFields != null && stamper.AcroFields.GenerateAppearances == true)