when i try to upgrade from DNN 5.5.1 to 5.6.3 the below error pops up ..

00:00:00.015 - Executing Script: 05.06.00.SqlDataProvider Error! (see 05.06.00.log.resources for more information)

the log file reveals the below error...

System.Data.SqlClient.SqlException: 'FK_ModuleControls_ModuleDefinitions' is not a constraint.
Could not drop constraint. See previous errors.
   at System.Data.SqlClient.SqlConnection. (SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.SqlInternalConnection. (SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at DotNetNuke.Data.SqlDataProvider.ExecuteADOScript(String SQL)
   at DotNetNuke.Data.SqlDataProvider.ExecuteScript(String Script, Boolean UseTransactions)



/* DNN-13285 -    Clustered Primary Key for ModuleDefinitions  */
/*************************************************************/

if not exists (select * from dbo.sysobjects where id = object_id(N'PK_ModuleDefinitions') and OBJECTPROPERTY(id, N'CnstIsClustKey') = 1)
    begin
        alter table dbo.[Modules]
            drop constraint FK_Modules_ModuleDefinitions

        alter table dbo.[ModuleControls]
            drop constraint FK_ModuleControls_ModuleDefinitions

        alter table dbo.[ModuleDefinitions]
            drop constraint PK_ModuleDefinitions

        alter table dbo.[ModuleDefinitions]
            add constraint PK_ModuleDefinitions
                primary key clustered (ModuleDefID asc ) on [PRIMARY]

        alter table dbo.[ModuleControls]
            add constraint FK_ModuleControls_ModuleDefinitions
                foreign key ( ModuleDefID ) references dbo.[ModuleDefinitions] ( ModuleDefID )
                on update no action
                on delete cascade

        alter table dbo.[Modules]
            add constraint FK_Modules_ModuleDefinitions
                foreign key ( ModuleDefID ) references dbo.[ModuleDefinitions] ( ModuleDefID )
                on update no action
                on delete cascade
    end

-----------------------

how can i resolve this issue?