Exception from HRESULT: 0x800A03EC Error

Question

I am getting "HRESULT: 0x800A03EC" error when running Excel add-in with following code:

Excel.Range rng = ActiveSheet.Cells[x, y] as Excel.Range;                
string before = rng.Value2; 
string cleanV = System.Text.RegularExpressions.Regex.Replace(before, @"\s+", "");
rng.set_Value(cleanV);

When error happens X and Y are set to 1, thus Excel range is not violated. I searched extensively and tried a number of ways of setting the cell value (eg. Cells[x,y], range.set_Value()) but am at loss why this error happens and how to avoid it.

Any help is greatly appreciated.

Below are exception details:

---

System.Runtime.InteropServices.COMException was unhandled by user code
  HResult=-2146827284
  Message=Exception from HRESULT: 0x800A03EC
  Source=""
  ErrorCode=-2146827284
  StackTrace:
       at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData)
       at Microsoft.Office.Interop.Excel.Range.set_Value(Object RangeValueDataType, Object value)
       at ImportValidation.ThisAddIn.removeAnySpaces(Int32 x, Int32 y) in c:\Users\dshevelev\Documents\Visual Studio 2012\Projects\ImportValidation\ImportValidation\ThisAddIn.cs:line 354
       at ImportValidation.ThisAddIn.ReadHeaders(Hashtable columnAddress) in c:\Users\dshevelev\Documents\Visual Studio 2012\Projects\ImportValidation\ImportValidation\ThisAddIn.cs:line 123
       at ImportValidation.ThisAddIn.mapColumns() in c:\Users\dshevelev\Documents\Visual Studio 2012\Projects\ImportValidation\ImportValidation\ThisAddIn.cs:line 493
       at ImportValidation.Ribbon1.button6_Click(Object sender, RibbonControlEventArgs e) in c:\Users\dshevelev\Documents\Visual Studio 2012\Projects\ImportValidation\ImportValidation\Ribbon1.cs:line 55
       at Microsoft.Office.Tools.Ribbon.RibbonPropertyStorage.ControlActionRaise(IRibbonControl control)
       at Microsoft.Office.Tools.Ribbon.RibbonPropertyStorage.ButtonClickCallback(RibbonComponentImpl component, Object[] args)
       at Microsoft.Office.Tools.Ribbon.RibbonManagerImpl.Invoke(RibbonComponentCallback callback, Object[] args)
       at Microsoft.Office.Tools.Ribbon.RibbonMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
       at Microsoft.Office.Tools.Ribbon.RibbonManagerImpl.System.Reflection.IReflect.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParameters)
  InnerException: 

Answer 1

Got same error in this line

 Object temp = range.Cells[i][0].Value;

Solved with non-zero based index

 Object temp = range.Cells[i][1].Value;

How is it possible that the guys who created this library thought it was a good idea to use non-zero based indexing?