Hi
I now found that simple code crashes
Workbook book = new Workbook("template.xlsx");
book.Save("saved.xlsx");
 
with ANY xlsx file
attached template.xlsx is a simple file for testing
Aspose 7.4.1.2
Linux and Mono information
uname -r
2.6.18-274.el5
cat /etc/*-release
CentOS release 5.7 (Final)
mono -V
Mono JIT compiler version 2.11.4 (tarball Wed Mar 13 12:16:33 OMST 2013)
Copyright (C) 2002-2012 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
        TLS:           __thread
        SIGSEGV:       altstack
        Notifications: epoll
        Architecture:  amd64
        Disabled:      none
        Misc:          softdebug
        LLVM:          supported, not enabled.
        GC:            Included Boehm (with typed GC and Parallel Mark)
 
 
Crush stack trace
Unknown heap type: SmartAssembly
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
  at �.��.�� (System.String , Single , FontStyle ) [0x00000] in :0
  at �.�. (System.String , Aspose.Cells.Font , Double ) [0x00000] in :0
  at �.�.�� (System.Drawing.Graphics , Aspose.Cells.Cells , Int32 , Int32 , Int32 , Int32 , Aspose.Cells.AutoFitterOptions ) [0x00000] in :0
  at �.�.AutoFitRow (Aspose.Cells.Cells , Int32 , Int32 , Int32 , Int32 , Aspose.Cells.AutoFitterOptions ) [0x00000] in :0
  at Aspose.Cells.Worksheet.AutoFitRow (Int32 rowIndex) [0x00000] in :0
  at �.�.�� (Aspose.Cells.Worksheet ) [0x00000] in :0
  at ..� (Aspose.Cells.WorksheetCollection ) [0x00000] in :0
  at .. () [0x00000] in :0
  at ..Write () [0x00000] in :0
  at ..� (Aspose.Cells.Workbook , System.IO.Stream , FileFormatType , Aspose.Cells.SaveOptions ) [0x00000] in :0
  at Aspose.Cells.Workbook.Save (System.IO.Stream stream, Aspose.Cells.SaveOptions saveOptions) [0x00000] in :0
  at Aspose.Cells.Workbook.Save (System.String fileName, Aspose.Cells.SaveOptions saveOptions) [0x00000] in :0
[ERROR] FATAL UNHANDLED EXCEPTION: System.NullReferenceException: Object reference not set to an instance of an object
  at �.��.�� (System.String , Single , FontStyle ) [0x00000] in :0
  at �.�. (System.String , Aspose.Cells.Font , Double ) [0x00000] in :0
  at �.�.�� (System.Drawing.Graphics , Aspose.Cells.Cells , Int32 , Int32 , Int32 , Int32 , Aspose.Cells.AutoFitterOptions ) [0x00000] in :0
  at �.�.AutoFitRow (Aspose.Cells.Cells , Int32 , Int32 , Int32 , Int32 , Aspose.Cells.AutoFitterOptions ) [0x00000] in :0
  at Aspose.Cells.Worksheet.AutoFitRow (Int32 rowIndex) [0x00000] in :0
  at �.�.�� (Aspose.Cells.Worksheet ) [0x00000] in :0
  at ..� (Aspose.Cells.WorksheetCollection ) [0x00000] in :0
  at .. () [0x00000] in :0
  at ..Write () [0x00000] in :0
  at ..� (Aspose.Cells.Workbook , System.IO.Stream , FileFormatType , Aspose.Cells.SaveOptions ) [0x00000] in :0
  at Aspose.Cells.Workbook.Save (System.IO.Stream stream, Aspose.Cells.SaveOptions saveOptions) [0x00000] in :0
  at Aspose.Cells.Workbook.Save (System.String fileName, Aspose.Cells.SaveOptions saveOptions) [0x00000] in :0