Hello,
We observed multiple NullReferenceExceptions when extracting from different files and would be happy when you fix them to make GroupDocs.Search more reliable.
1. .doc file
at \u0006\u001A\u0018\u0015.\u0008()
at \u0006\u001A\u0018\u0015..ctor(\u000F\u0019\u0005\u001A \u0002, ILoadOptions \u0008)
at \u0008\u0010\u0016\u0002.\u0002(\u000F\u0019\u0005\u001A \u0002, InterruptionToken \u0008)
at Aspose.Slides.Presentation.\u0002(\u000F\u0019\u0005\u001A \u0002)
at Aspose.Slides.Presentation.\u0002(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation..ctor(Stream stream, LoadOptions loadOptions)
at \u0006\u0018\u0003.\u0002(Stream \u0002, LoadOptions \u0008)
at \u000F\u0003\u0003.\u0002()
at \u000F\u0003\u0003.\u000F\u0010\u001A\u0003\u0016\u0002(Nullable`1 \u0002, TextOptions \u0008)
at GroupDocs.Parser.Parser.GetText(TextOptions options)
at \u0006\u0019\u0002.\u000E\u0018\u001B\u0003\u0016\u0002(String \u0002, Boolean \u0008)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
2. .pdf file
at Aspose.Pdf.Annotations.DocumentActionCollection..ctor(Document document)
at Aspose.Pdf.Document.#=zMRs5bt4=()
at Aspose.Pdf.Document.#=zMRs5bt4=(Stream #=zMgMAfoc=, String #=zK7jLnng=)
at Aspose.Pdf.Document..ctor(Stream input)
at \u0006\u0018\u0005.\u0002(Stream \u0002, LoadOptions \u0003)
at \u0006\u0017\u0005.\u0008\u0017\u0003\u0017\u0005\u0017\u0015\u0002()
at GroupDocs.Parser.Parser.GetMetadata()
at \u000F\u0002\u0010.\u000E\u001A\u000F\u0016\u0005\u0003()
at \u0003\u0016\u000F.\u0002(Document \u0002, \u0006\u001A\u000F \u0003, String \u0005)
3. .odp file
at \u0005\u0003\u0002\u0015.\u0002(String \u0002, \u0008\u0019\u0005\u0018 \u0008, \u0002\u001A\u001B\u0003 \u0005, \u0002\u001A\u001B\u0003 \u0006)
at \u0005\u0003\u0002\u0015.\u0002(ShapeCollection \u0002, \u0008\u0016\u0017\u0018 \u0008, \u0008\u001A\u0017\u0018 \u0005, \u000F\u0002\u0002\u0015 \u0006)
at \u0003\u0002\u000F\u0015.\u0002(ShapeCollection \u0002, \u0008\u0016\u0017\u0018 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u0003\u0002\u000F\u0015.\u0006(ShapeCollection \u0002, Object \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u0003\u0002\u000F\u0015.\u0002(ShapeCollection \u0002, \u0002\u0003\u000F\u0002 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u000F\u0002\u000F\u0015.\u0002(Slide \u0002, \u0003\u001A\u0017\u0018 \u0008, IList`1 \u0005, \u0006\u001B\u0002\u0015 \u0006)
at \u0008\u0002\u000F\u0015.\u0002(Presentation \u0002, \u0006\u0003\u0003\u0003 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u000E\u0003\u0002\u0015.\u0002(Presentation \u0002)
at \u0002\u001A\u0002\u0015.\u0003(\u000F\u001A\u0016\u001A \u0002, Presentation \u0008)
at \u0002\u001A\u0002\u0015.\u0002(Presentation \u0002, Stream \u0008, InterruptionToken \u0005, Boolean \u0006)
at Aspose.Slides.Presentation.\u0008(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation.\u0002(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation..ctor(Stream stream, LoadOptions loadOptions)
at \u0006\u0018\u0003.\u0002(Stream \u0002, LoadOptions \u0008)
at \u000F\u0003\u0003.\u000F\u0010\u001A\u0003\u0016\u0002(Nullable`1 \u0002, TextOptions \u0008)
at GroupDocs.Parser.Parser.GetText(TextOptions options)
at \u0008\u001B\u001B.\u0002(Document \u0002, \u0003\u0018\u001B \u0008, String \u0005)
4. .docx file
at \u0005\u0003\u0002\u0015.\u0002(IChartSeries \u0002, Boolean \u0008, \u0006\u0019\u0005\u0018 \u0005, \u0006\u001B\u0002\u0015 \u0006)
at \u0005\u0003\u0002\u0015.\u0002(Chart \u0002, \u0008\u0019\u0005\u0018 \u0008, \u0002\u001A\u001B\u0003 \u0005, \u0002\u001A\u001B\u0003 \u0006, \u0006\u001B\u0002\u0015 \u0003)
at \u0005\u0003\u0002\u0015.\u0002(ShapeCollection \u0002, \u0008\u0016\u0017\u0018 \u0008, \u0008\u001A\u0017\u0018 \u0005, \u000F\u0002\u0002\u0015 \u0006)
at \u0003\u0002\u000F\u0015.\u0002(ShapeCollection \u0002, \u0008\u0016\u0017\u0018 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u0003\u0002\u000F\u0015.\u0006(ShapeCollection \u0002, Object \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u0003\u0002\u000F\u0015.\u0002(ShapeCollection \u0002, \u0002\u0003\u000F\u0002 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u000F\u0002\u000F\u0015.\u0002(Slide \u0002, \u0003\u001A\u0017\u0018 \u0008, IList`1 \u0005, \u0006\u001B\u0002\u0015 \u0006)
at \u0008\u0002\u000F\u0015.\u0002(Presentation \u0002, \u0006\u0003\u0003\u0003 \u0008, \u0006\u001B\u0002\u0015 \u0005)
at \u000E\u0003\u0002\u0015.\u0002(Presentation \u0002)
at \u0002\u001A\u0002\u0015.\u0003(\u000F\u001A\u0016\u001A \u0002, Presentation \u0008)
at \u0002\u001A\u0002\u0015.\u0002(Presentation \u0002, Stream \u0008, InterruptionToken \u0005, Boolean \u0006)
at Aspose.Slides.Presentation.\u0008(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation.\u0002(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation..ctor(Stream stream, LoadOptions loadOptions)
at \u0006\u0018\u0003.\u0002(Stream \u0002, LoadOptions \u0008)
at \u000F\u0003\u0003.\u0002()
at \u000F\u0003\u0003.\u000F\u0010\u001A\u0003\u0016\u0002(Nullable`1 \u0002, TextOptions \u0008)
at GroupDocs.Parser.Parser.GetText(TextOptions options)
at \u0002\u0019\u0002.\u0002(Parser \u0002, Boolean \u0008, FileFormat \u0005)
at \u0006\u0019\u0002.\u000E\u0018\u001B\u0003\u0016\u0002(String \u0002, Boolean \u0008)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
5. .one file
at \u0008\u0015\u0017.\u0002()
at \u0008\u0015\u0017.\u0002\u0015\u0017\u0016\u0016\u0002()
at \u0003\u001B\u0019.\u0002(Stream \u0002, Document \u0003, LoadOptions \u0005)
at Aspose.Note.Document.\u0002(Stream \u0002, LoadOptions \u0003)
at Aspose.Note.Document..ctor(Stream inStream, LoadOptions loadOptions)
at \u0006\u0010\u0003.\u0002(Stream \u0002, LoadOptions \u0008)
at \u0005\u0010\u0003.\u0002()
at \u0005\u0010\u0003.\u000F\u0010\u001A\u0003\u0016\u0002(Nullable`1 \u0002, TextOptions \u0008)
at GroupDocs.Parser.Parser.GetText(TextOptions options)
at \u0008\u001B\u001B.\u0002(Document \u0002, \u0003\u0018\u001B \u0008, String \u0005)
6. .ppt file
at \u0003\u0017\u0016\u0002.\u0005\u000F()
at \u0003\u0017\u0016\u0002.\u0002()
at \u0005\u0015\u0016\u0002.\u0002(\u0003\u0017\u0016\u0002 \u0002)
at \u0008\u0010\u0016\u0002.\u000E\u000F()
at \u0008\u0010\u0016\u0002.\u0002(\u000F\u0019\u0005\u001A \u0002, InterruptionToken \u0008)
at Aspose.Slides.Presentation.\u0002(\u000F\u0019\u0005\u001A \u0002)
at Aspose.Slides.Presentation.\u0002(Stream \u0002, Boolean \u0008)
at Aspose.Slides.Presentation..ctor(Stream stream, LoadOptions loadOptions)
at \u0006\u0018\u0003.\u0002(Stream \u0002, LoadOptions \u0008)
at \u000F\u0003\u0003.\u0002()
at \u000F\u0003\u0003.\u000F\u0010\u001A\u0003\u0016\u0002(Nullable`1 \u0002, TextOptions \u0008)
at GroupDocs.Parser.Parser.GetText(TextOptions options)
at \u0008\u001B\u001B.\u0002(Document \u0002, \u0003\u0018\u001B \u0008, String \u0005)
7. .xlsx file
at \u0006\u001A\u0003.\u0002(\u0005\u0018\u001A \u0002, \u0003\u001A\u0003 \u0008)
at \u0006\u001A\u0003.\u0008(\u0005\u0018\u001A \u0002, \u0003\u001A\u0003 \u0008)
at GroupDocs.Parser.Data.ContainerItem.OpenParser(LoadOptions loadOptions, ParserSettings parserSettings)
at \u000E\u0005\u0002.\u0006\u0018\u001B\u0003\u0016\u0002(\u0002\u0005\u001B \u0002, \u0008\u0017\u0002 \u0008, String \u0005)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
8. .xls file
at \u000E\u0018\u0003.\u0006\u0017\u001A\u0003\u0016\u0002(ContainerItem \u0002)
at GroupDocs.Parser.Data.ContainerItem.OpenParser(LoadOptions loadOptions, ParserSettings parserSettings)
at GroupDocs.Parser.Data.ContainerItem.OpenParser(LoadOptions loadOptions)
at \u0006\u0019\u0002..ctor(\u0002\u0005\u001B \u0002, \u0008\u0017\u0002 \u0008, FileFormat \u0005, \u0005\u000F\u0002 \u0006, ContainerItem \u0003, String \u000E)
at \u000E\u0005\u0002.\u0006\u0018\u001B\u0003\u0016\u0002(\u0002\u0005\u001B \u0002, \u0008\u0017\u0002 \u0008, String \u0005)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
at \u0008\u001B\u001B.\u0002(Document \u0002, \u0003\u0018\u001B \u0008, String \u0005)
9. .xlsm file
at \u000E\u0018\u0003.\u0006\u0017\u001A\u0003\u0016\u0002(ContainerItem \u0002)
at GroupDocs.Parser.Data.ContainerItem.OpenParser(LoadOptions loadOptions, ParserSettings parserSettings)
at GroupDocs.Parser.Data.ContainerItem.OpenParser(LoadOptions loadOptions)
at \u0006\u0019\u0002..ctor(\u0002\u0005\u001B \u0002, \u0008\u0017\u0002 \u0008, FileFormat \u0005, \u0005\u000F\u0002 \u0006, ContainerItem \u0003, String \u000E)
at \u000E\u0005\u0002.\u0006\u0018\u001B\u0003\u0016\u0002(\u0002\u0005\u001B \u0002, \u0008\u0017\u0002 \u0008, String \u0005)
at \u0008\u001B\u001B.\u0002(Int32 \u0002, \u0006\u0018\u001B \u0008)
at \u0008\u001B\u001B.\u0002(Document \u0002, \u0003\u0018\u001B \u0008, String \u0005)