Error : System.IO.IOException: block[ 2 ] already removed at NPOI.POIFS.Storage.BlockListImpl.Remove(Int32 index)
Some information on this error can be found here: https://bz.apache.org/bugzilla/show_bug.cgi?id=55124
It looks like it is caused by non-standard spreadsheet editing software. This can be resolved by copy pasting the data into a new spreadsheet using spreadsheet software known to be good e.g. Excel 2013.