I just had a great call with dell. They are working on a fix. As workaround try this:-  Rename the server.xml of "C:\Program Files\DELL\WMS\Tomcat-9\conf" to e.g. serverold.xml- Go to "C:\Program Files\DELL\WMS\Archive" and copy this server.xml- Paste it in to "C:\Program Files\DELL\WMS\Tomcat-9\conf"- Start the tomcat service and wait for a few sec- Try to login
I have just installed the new hotfix for WMS 3.1 and I am now getting an Error 1607:The process terminated unexpectedley when starting the Dell WMS: Tomcat Service. Not sure why and unable to rollback which means that I can now not access the WMS Portal at all. So beware when upgrading!  I should have created a snapshot before trying but stupidly did not!  
WMS 3.1 HotFix 1 upgrade has broken Tomcat Service