Need to upgrade my VE from version 10.2.4 to version 11.5.2.0

Firstly, I would recommend that you choose 11.5.3 rather than 11.5.2. 11.5.x follows the new release cycle described here:

https://support.f5.com/kb/en-us/solutions/public/8000/900/sol8986.html

Specifically, it is the "long-term stability release" for 11.x (note that no other 11.x minor releases follow this new model). As such, 11.5.2 is now past end-of-software development. Any security fixes, stability improvements and new hardware support will be in following maintenance releases of 11.5.x. See this solution article for details:

https://support.f5.com/kb/en-us/solutions/public/5000/900/sol5903.html

You may find it instructive to discuss this new version model with your F5 Account team, since it is significantly different than the legacy release model.

Having said all of that, the jump from 10.2.4 to 11.5.2 can be done, but there are indeed a few things of which you'll want to be mindful:

1. HTTP Classes are no longer supported. If you are using HTTP Classes, you will need to remove them then re-add them (as iRules or Local Traffic Policies) after the upgrade;
2. external monitors and certificates have moved. They should port, but it is prudent to double-check them if the update succeeds to ensure that they are working as expected;
3. some GTM items -- particularly BIND records -- can have some issues on upgrade, but if you don't have GTM provisioned, or do not use ZoneRunner directly to manage zones or records (allowing GTM to create and remove them) you will likely be fine;
4. there are some things that were inadvertently allowed for GTM object names under 10.x that will simply fail on an upgrade attempt. Specifically, spaces were allowed for servers and pool names. If you have spaces, you must remove them before upgrading;
5. the GTM configuration files have been collapsed into a single file. This generally won't matter to you unless you are used to looking in

   /config/gtm

   for config items. It is now

   /config/bigip_gtm.conf

   ;
6. the Admin Partition configuration has been moved out of the general config files (e.g.,

   bigip.conf

   ) and moved to separate files under

   /config/partitions

   . Again, this likely won't matter to you unless you are used to seeing partition cross-references in the primary config files.

You may be able to glean additional insights by either opening a Support case and asking this same question, or by reaching out to your F5 Account Team, and asking your account FSE to do so on your behalf. If the upgrade fails, you may consider engaging F5 Professional Services for assistance. They are a for-pay consulting division of F5.