We have a Quick Fields session built about four years ago that uses Univeral Capture to get pdf documents into our repository. It has worked just fine until this month. Now we have 10 failures out of about 200 documents. All of the documents are on a shared drive in several subfolders with identical permissions, no one is in the folders while we run the process. The error message looks like it's a problem with locking the file but I can't find documentation to confirm or help fix. What am I missing?

Error: cannot scan '66_S.L. 1429 L.L.C._381037.pdf'. System.ArgumentException: session
   at Laserfiche.RepositoryAccess.SessionHelper.GetLockForId(ISession session, Int32 entryId)
   at Laserfiche.RepositoryAccess.AnnotationBase.get_LockToken()
   at Laserfiche.RepositoryAccess.AttachmentAnnotation.AttachmentWriteStream..ctor(AttachmentAnnotation ann, HttpUrl url, Int64 size)
   at Laserfiche.RepositoryAccess.AttachmentAnnotation.GetAttachmentWriter(String mimeType, Int64 size)
   at Laserfiche.PdfServices.AnnotsImporter.CreateAttachmentAnnFromFileSpecDict(PdfDictionary fsDict, PdfDictionary annotDict, PageInfo page)
   at Laserfiche.PdfServices.AnnotsImporter.ConvertAttachmentAnnotation(PdfDictionary annotDict, PageInfo page)
   at Laserfiche.PdfServices.AnnotsImporter.ImportPDFPageAnnotsWithiTextSharp(PdfDictionary pageDict, DocumentInfo doc, PageInfo page)
   at Laserfiche.PdfServices.AnnotsImporter.ImportPDFAnnotsWithiTextSharp(PdfReader pdfReader, DocumentInfo doc)
   at Laserfiche.PdfServices.PdfExtractor.ImportPDFPagesFromStream(Stream pdfStream, DocumentInfo doc)
   at Laserfiche.PdfServices.PdfExtractor.ImportPDFStream(Stream pdfStream, DocumentInfo doc, DateTime dtLastModified)
   at Laserfiche.PdfServices.PdfExtractor.ImportPDFFile(String strPDFFile, DocumentInfo doc)
   at BPPDFImporter83.PDFImporter.ImportPDF(IBPDocumentEx documentEx)