Repaired Records : Cell information from worksheet created from scratch

If you are adding a string to a cell rather than a number (or a string that can be converted to a number) then you should use an inline string or a shared string instead of the CellValue. You can only use CellValue if the value is numeric.

The XML generated when using CellValue looks something like:

<x:row>
  <x:c>
    <x:v>12345</x:v>
  </x:c>
</x:row>

when you use an inline string it looks like:

<x:row>
  <x:c t="inlineStr">
    <x:is>
      <x:t>Foo</x:t>
    </x:is>
  </x:c>
</x:row>

note the "is" node for inline string and that the cell type attribute is set to "inlineStr".

Here is C# code to generate correct XML for a cell containing text:

cell.DataType = CellValues.InlineString;
cell.InlineString = new InlineString() { Text = new Text(textToInsert) };

From what I have read using shared strings is preferable but using inline strings avoids the error and looks just fine when you open the file in Excel.

My issue was that I had been setting the name of the worksheet with a name that had a forward slash / in it.