C# DataSet Designer "Column requires a valid datatype" error but all types seem fine

I inherited the maintenance task of a broken dataset in C# and Visual Studio gives me the error message "Column requires a valid datatype" error. I cannot open the dataset designer and changes to the XML file lead to a deletion of the the MyDataSet.Designer.cs, because the XML cannot be parsed. The error occurs deep in the XML parsing so I cannot gain any开发者_高级运维 additinoal information which column type actually fails.

For reference, I am using MySQL Connector/NET 6.3.6 and .NET 4

This is where i started to extract all the exisiting types out of the XML (DbType and ProviderType attributes). These are the values and how often they exist:

Database-Types:
---------------
   StringFixedLength       4
               Int64      12
                Date      20
               SByte      32
              Single      44
          AnsiString      54
            DateTime      96
              String     300
               Int32     432
Provider-Types:
---------------
              String       4
               Int64      12
                Date      20
          NewDecimal      24
                Text      30
                Byte      32
               Float      44
           Timestamp      96
             VarChar     300
               Int32     432

The DbTypes all seem perfectly valid according to the DbTypeEnumeration docs http://msdn.microsoft.com/en-us/library/system.data.dbtype.aspx.

I am not sure about the ProviderTypes, but they look ok also.

Does someone have a clue either how to debug this problem or even how to fix it?