How to fix “Not a legal OleAut date.” when reading an Excel file in C#?

Question

I have been working with excel spreadsheets and so far I never had any problems with them.. But this error,"Not a legal OleAut date.", showed up out of the blue when I tried to read an excel file. Does anyone know how I can fix this. Here is the code I use to read the excel and put the data into a dataset. It has worked fine previously but after I made some changes (which doesn't involve dates) to the data source this error showed up.

var fileName = string.Format("C:\\Drafts\\Excel 97-2003 formats\\All Data 09 26 2012_Edited.xls");
        var connectionString = string.Format("Provider=Microsoft.Jet.OLEDB.4.0; data source={0}; Extended Properties=Excel 8.0;", fileName);

        var adapter = new OleDbDataAdapter("SELECT * FROM [Sheet1$]", connectionString);

        DataSet Originalds = new DataSet();
        adapter.Fill(Originalds, "Employees"); // this is where the error shows up

Answer 1

I sort of figured out a work around to this problem I changed the connection string to the latest oleDB provider.

var connectionString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 12.0 Xml;HDR=YES;'", fileName);

I also made sure that the empty space after the last row of my excel data is not being read as a value.

Answer 2

Look for different date formats, in my case one of the column was in dd/mm/yyyy format and the other was in mm/dd/yyyy. Once the date formats were rectified data import worked.

Answer 3

In my case, I had a date in my table inserted manually with the wrong format, it was 01/01/0019 instead of 01/01/2019.