I have just upgraded an Umbraco 6.0.3 site running on MySql to 6.1.6 running on MS Sql 2012 and everything seems to be working. The database conversion was done manually by exporting data as csv and importing it to MS Sql.

But the UmbracoTraceLog is full of the exact same error. Every minute I see the following entry:

2013-10-27 09:49:36,554 [15] INFO  Umbraco.Core.Persistence.UmbracoDatabase - [Thread 29]    at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlDataReader.TryHasMoreRows(Boolean& moreRows)
   at System.Data.SqlClient.SqlDataReader.TryReadInternal(Boolean setTimeout, Boolean& more)
   at System.Data.SqlClient.SqlDataReader.Read()
   at Umbraco.Core.Persistence.Database.<Query>d__1c`1.MoveNext()

What is causing this error and how do I fix it?

The site is running on a Windows 2008 R2 server with IIS 7, .Net 4.5 and MS Sql 2012