Just some notes relating to error codes received during Sharepoint integration using the UpdateListItems method of the  lists.asmx service.

A value in the update for a column exceeded the maximum column size.

<ErrorCode xmlns="http://schemas.microsoft.com/sharepoint/soap/">0x81020018</ErrorCode>
<ErrorText xmlns="http://schemas.microsoft.com/sharepoint/soap/">Invalid text value

A text field contains invalid data. Please check the value and try again.</ErrorText>

A column to be updated was passed in that did not exist.

<ErrorCode xmlns="http://schemas.microsoft.com/sharepoint/soap/">0x81020014</ErrorCode>
<ErrorText xmlns="http://schemas.microsoft.com/sharepoint/soap/">One or more field types are not installed properly. Go to the list settings page to delete these fields.</ErrorText>
  </Result>

The field being updated was a lookup field that allows multiple values and the value passed in contained a trailing ";".  A trailing semi-colon only seems to be an issue when it is the first item in the list.

<!-- <Field Name="VehicleFeatures">1,#Cassette Radio;</Field> -->
<ErrorCode xmlns="http://schemas.microsoft.com/sharepoint/soap/">0x80070057</ErrorCode>
<ErrorText xmlns="http://schemas.microsoft.com/sharepoint/soap/">Bad parameter passed to Web Server Extensions.  Check the information you entered and try again.</ErrorText>
</Result>