This can occur when sourcing the siebenv.sh as root then later trying as the installation user:

It may be best to reboot the VM prior to doing the steps below.

1. Backup the regss15: files in the /tmp directory, Example:

   cd /tmp
   mv regss15:123483357904896 regss15:123483357904896.bak
   mv regss15:123483357904896.pid regss15:123483357904896.pid.bak
   
   

2. Login as root, change the ownership of watchdog.keepalive (or just do the entire directory)

   cd /u01/app/ses/siebsrvr/mw/.mw/core_data/devtwosblsrvr/
   chown -R siebel:sgroup .
   
   

3. Try to source siebenv.sh again as oracle

   [siebel@devtwo siebsrvr]# . ./siebenv.sh