Convert list item attachment from docx to pdf using Word Automation Services

Question

I have been trying to convert List Item attachments from docx to pdf using word automation services, it works in a normal document library but when I use the list attachment it throws a null reference error.
var settings = new ConversionJobSettings();
settings.OutputFormat = Microsoft.Office.Word.Server.Conversions.SaveFormat.PDF;
var conversion = new ConversionJob("Word Automation Services", settings);
conversion.UserToken = SPContext.Current.Site.UserToken;
var wordFile = SPContext.Current.Site.RootWeb.Url + "/" + wordForm.Url;
var pdfFile = wordFile.Replace(".docx", ".pdf");
conversion.AddFile(wordFile, pdfFile);
conversion.Start();
Using reflector I was able to see my problem lies in Microsoft.Office.Word.Server.FolderIterator.cs where it uses SPFile.Item which returns NULL
internal void CheckSingleItem(SPFile inputFile, SPFile outputFile)
Microsoft.Office.Word.Server.Log.TraceTag(0x67337931, Microsoft.Office.Word.Server.Log.Category.ObjectModel, Microsoft.Office.Word.Server.Log.Level.Verbose, "OM: FolderIterator start a single item: source='{0}'; dest='{1}'", new object[] { inputFile.Url, outputFile.Url });
Stopwatch stopwatch = Microsoft.Office.Word.Server.Log.StartPerfStopwatch();
try
this.CheckInputFile(inputFile.Item);
this.CheckOutputFile(outputFile.Url);
Is there any way to get around this?

Answer 1

Hi Qfroth,
According to your description, my understanding is that when you use word automation service to convert Word to PDF for list item attachment, it throws the null reference error.
I suggest you can create an event receiver and convert the word to memory stream like below:
private byte[] ConvertWordToPDF(SPFile spFile, SPUserToken usrToken)
byte[] result = null;
try
using (Stream read = spFile.OpenBinaryStream())
using (MemoryStream write = new MemoryStream())
// Initialise Word Automation Service
SyncConverter sc = new SyncConverter(WORD_AUTOMATION_SERVICE);
sc.UserToken = usrToken;
sc.Settings.UpdateFields = true;
sc.Settings.OutputFormat = SaveFormat.PDF;
// Convert to PDF
ConversionItemInfo info = sc.Convert(read, write);
if (info.Succeeded)
result = write.ToArray();
catch (Exception ex)
// Do your error management here.
return result;
Here is a detailed code demo for your reference:
Word to PDF Conversion using Word Automation Service
Best Regards
Zhengyu Guo
TechNet Community Support