How to connect TrueSight Automation Console 20.02 (OnPrem TSAC) and Helix Automation Console 20.02 (SaaS) or Helix Vulnerability Management 20.02 (SaaS) to TrueSight Server Automation (TSSA) 8.9.04.(P1-P3)?
By default these products/solutions can connect to TSSA 20.02.
TSAC 20.02 Documentation System Requirements

TSAC 19.1/Helix Automation Console 19.11 supports TSSA end point manager version TSSA 8.9.04.01.
TSAC 20.02/Helix Automation Console 20.02 supports TSSA end point manager version TSSA 20.02
Below steps can be taken to connect to TSSA 8.9.04.P1-P3 (8.9.4 GA is not supported) from TSAC 20.02 or Helix AC 20.02:

• Download the ZIP file from the FTP location ftp://ftp.bmc.com/pub/tsac/TSSA20.02_GA_REST.zip
• Extract the contents to a temporary location.
• Stop TSSA AppServer.
• Navigate to :
  • Windows: <TSSA-Install-Dir>/NSH\br\deployments\default\tomcat\webapps\
  • Linux: <TSSA-Install-Dir>/NSH/br/deployments/default/tomcat/webapps
• Take a backup of the existing rest.war file in another folder outside of webapps. If you see a folder called rest then move the contents to another folder outside of webapps.
• Copy the downloaded and extracted rest.war from the temporary location to this webapps folder.
• Start TSSA App Server.
• Restart TSAC DB and Appservice.

Example:
[root@TSAC-Db-App ~]#
cd /opt/bmc/ [root@TSAC-Db-App bmc]
# ./stackmanager stop  --deployment=database
[root@TSAC-Db-App bmc
]# ./stackmanager start  --deployment=database
[root@TSAC-Db-App bmc]
# ./stackmanager stop  --deployment=application
[root@TSAC-Db-App bmc]
# ./stackmanager start  --deployment=application

Now TSAC 20.02 or Helix AC 20.02 can connect to TSSA 8.9.04 Px.

Checksum of the files:
cksum TSSA20.02_GA_REST.zip
1148767430 30208789 TSSA20.02_GA_REST.zip
cksum rest.war
4012783748 30331691 rest.war