Connect as SYS Schema
SQL> conn sys@<DB> / as sysdba
Then execute below commands:
SQL> execute sys.dbms_metadata_util.load_stylesheets;
<multicast channel="228.5.6.7" port="14021" timeout="1000" retry="5"/>
<!--namingService name="Cos" host="127.0.0.1" port="14021"/-->
<!--multicast channel="228.5.6.7" port="14021" timeout="1000" retry="5"/-->
<namingService name="Cos" host="127.0.0.1" port="14021"/>
C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\Binn\TemplatesC:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA