REP-51019: System user authentication is missing

Solution:
First take a back/rename up of your rwserver.conf original file.


Some changes required in rwserver.conf
remove security tag from

You will find the rwserver.conf file from the below path.


C:\Oracle\Middleware\Oracle_Home\user_projects\domains\Classic_domain\config\fmwconfig\components\ReportsServerComponent\Your_report_server_name\rwserver.conf


C:\Oracle\Middleware\Oracle_Home\user_projects\domains\Classic_domain\config\fmwconfig\servers\WLS_REPORTS\applications\reports_12.2.1\configuration\rwserver.conf


C:\Oracle\Middleware\Oracle_Home\user_projects\domains\Classic_domain\config\fmwconfig\components\ReportsToolsComponent\reptools1\rwserver.conf


<job jobType="report" engineId="rwEng" securityId="rwJaznSec"/>
to
<job jobType="report" engineId="rwEng"/>

Also,

Comment the line below from
<security id="rwJaznSec" class="oracle.reports.server.RWJAZNSecurity"/> 

to 

<!--security id="rwJaznSec" class="oracle.reports.server.RWJAZNSecurity"/-->


1) Make single signon yes
2) Add <webcommandaccess>L2</webcommandaccess> in oracle/user_projects/domains/forms_domain/config/fmwconfig/servers/WLS_REPORTS/applications/reports_12.2.1/configuration/rwservlet.properties


Restart your Report Server….

Note: Change all path as per your configurations