I know that this solution is a little different from the OP's case, but as you may have been redirected here from searching on google the title of this question, as I did, maybe you're facing the same problem I had.
Sometimes you get this error because your date time is not valid, i.e. your date (in string format) points to a day which exceeds the number of days of that month!
e.g.: CONVERT(Datetime, '2015-06-31')
caused me this error, while I was converting a statement from MySql (which didn't argue! and makes the error really harder to catch) to SQL Server.