Up to and including version 17.5 Plesk Onyx came with a Tomcat installation, which is no longer supported from version 17.8. Thus no .war files can be deployed and executed anymore.
A downgrade recommended by Plesk is not expedient in my eyes, because of the near end of life and security concerns. How can I run Java code on a Plesk-managed server?
Use a Tomcat Docker container instead and deploy your .war file in a mapped Docker volume.
Home -> Server Management -> Extensions -> search textbox).Home -> Server Management -> Docker).search textbox -> 'run' drop down box)"Automatic start after system reboot""Automatic port mapping""Manual mapping" choose a 8080 to external 8080 port configuration/usr/local/tomcat/webapps/ to /usr/local/tomcat/webapps/ /usr/local/tomcat/logs/ to /usr/local/tomcat/logs/The first volume mapping provides a directory on the host system (your server) which is synchronized with the webapps directory within the Tomcat container. Copying your .war file into it will deploy it at the Tomcat container. The second volume mapping provides the Tomcat container internal log files to your host system.