Upgrade Directly from 14.1.5 to 16.1.3

Hey @Asim_IIPL

As others have mentioned, every version is going to have bugs. Which ones impact you are going to be specific to your environment. That being said, I can share my experience as I went through a similar upgrade path a few months ago (14.1.5.1 to 16.1.3.4)

The main issue we had was a few of our virtuals were using TCP WAM profiles. This caused the upgrade to fail and it was a mess because it wouldn't load even after after manually modifying bigip.conf. We had to roll back, update the virtuals to use different profiles, then start the upgrade again. I recommend auditing your virtuals to see if any of them are using TCP WAM profiles and change them to another profile before you upgrade. This KB has more info: https://my.f5.com/manage/s/article/K30113094.

We also ran into a minor issue on our GTMs where several GTM pool members that were legitimately down would continuously log status change events going from a 'down' status to a 'down' status. This was only noticed because we had Splunk alerts that triggered off of these events. I can't find the bug but I'm almost positive it was fixed in 16.1.3.5. As a workaround, I ended up creating a log filter in syslog-ng settings.