title: Exception from HRESULT: 0x800A03EC Error
body: <p>I am getting "HRESULT: 0x800A03EC" error when running Excel add-in with following code:</p>
  
  <pre><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);
  </code></pre>
  
  <p>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.</p>
  
  <p>Any help is greatly appreciated.</p>
  
  <p>Below are exception details:</p>
  
  <hr>
  
  <pre><code>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&amp; 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: 
  </code></pre>