Config not transferred after upgrade to 11.6.0

Hi DP, since you're already running on 11.2.1 I don't see the need to rollback. Backup your current configuration, go for 11.6 and check for bigip.conf load issues in /var/log/ltm. As you correct them (usually syntax changes are well documented and a google search for the error will bring you to the SOL page that explains what to modify/delete), use the daol command to see if the system accepts the modified file.