I get this error when upgrading from umbraco 7.2.8 to 7.3.0. It bombs when it tries to create a unique index on the uniqueID field for the umbracoNode table. If I query this table I see that I have close to 2000 duplicate entries. I still have a backup of our umbraco 4.11 database and that too has the same duplicate entries. Maybe the data got corrupted over the years since we have been upgrading it for 2-3 years. Any ideas on what I need to do to fix this issue? A bigger question is what other data integrity issues do we have. It would be nice if there was some sort of dbcc type check in umbraco that would validate the database.

2015-10-08 23:38:33,703 [P4920/D32/T32] INFO  Umbraco.Core.Persistence.Migrations.MigrationRunner - Executing sql statement 17: CREATE UNIQUE NONCLUSTERED INDEX [IX_umbracoNode_uniqueID] ON [umbracoNode] ([uniqueID])

 2015-10-08 23:38:33,897 [P4920/D32/T32] INFO  Umbraco.Core.Persistence.UmbracoDatabase -    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.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at StackExchange.Profiling.Data.ProfiledDbCommand.ExecuteNonQuery() in c:\Code\github\SamSaffron\MiniProfiler\StackExchange.Profiling\Data\ProfiledDbCommand.cs:line 286
   at Umbraco.Core.Persistence.PetaPocoCommandExtensions.<>c__DisplayClass1.<ExecuteNonQueryWithRetry>b__0() in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\PetaPocoCommandExtensions.cs:line 56
   at Umbraco.Core.Persistence.FaultHandling.RetryPolicy.ExecuteAction[TResult](Func`1 func) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\FaultHandling\RetryPolicy.cs:line 172
   at Umbraco.Core.Persistence.Database.Execute(String sql, Object[] args) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\PetaPoco.cs:line 594
 2015-10-08 23:38:33,900 [P4920/D32/T32] ERROR Umbraco.Core.DatabaseContext - Database configuration failed
System.Data.SqlClient.SqlException (0x80131904): The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name 'dbo.umbracoNode' and the index name 'IX_umbracoNode_uniqueID'. The duplicate key value is (8fa52517-630d-44b9-ad12-00052c0101a4).
The statement has been terminated.
   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.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at StackExchange.Profiling.Data.ProfiledDbCommand.ExecuteNonQuery() in c:\Code\github\SamSaffron\MiniProfiler\StackExchange.Profiling\Data\ProfiledDbCommand.cs:line 286
   at Umbraco.Core.Persistence.PetaPocoCommandExtensions.<>c__DisplayClass1.<ExecuteNonQueryWithRetry>b__0() in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\PetaPocoCommandExtensions.cs:line 56
   at Umbraco.Core.Persistence.FaultHandling.RetryPolicy.ExecuteAction[TResult](Func`1 func) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\FaultHandling\RetryPolicy.cs:line 172
   at Umbraco.Core.Persistence.Database.Execute(String sql, Object[] args) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\PetaPoco.cs:line 608
   at Umbraco.Core.Persistence.Migrations.MigrationRunner.ExecuteMigrations(IMigrationContext context, Database database) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\Migrations\MigrationRunner.cs:line 278
   at Umbraco.Core.Persistence.Migrations.MigrationRunner.Execute(Database database, DatabaseProviders databaseProvider, Boolean isUpgrade) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\Persistence\Migrations\MigrationRunner.cs:line 126
   at Umbraco.Core.DatabaseContext.UpgradeSchemaAndData(IMigrationEntryService migrationEntryService) in c:\projects\umbraco-cms-xtjqd\src\Umbraco.Core\DatabaseContext.cs:line 670
ClientConnectionId:7b052691-bed0-4055-966d-772079751dd0
Error Number:1505,State:1,Class:16