Upgrades ( 11.3.x to 12.1.x)

I suggest you to follow this order:

1 - Software version

Choose the correct version using this solution:

https://support.f5.com/csp/article/K5903

2 - Release notes

Read the release notes for that version.

Here is the release notes for 12.1.2, as example:

https://support.f5.com/kb/en-us/products/big-ip_ltm/releasenotes/product/relnote-ltm-12-1-2.html

3 - iHeath

Generate a qkview, and upload to iHealth. Use the Upgrade Advisor option there. It will probably tell you that HTTP classes were replaced with LTM policies in the target version.

4 - Virtual Edition

Generate a UCS and load in a VE with the current version. You will need to fix some configuration to make it load, I suggest you to use the platform-migrate option to load the ucs.

https://support.f5.com/csp/article/K82540512

Concluding, is a considerable jump between 11.3.0 to 12.1.X.

Also, there is no version 11.3.2, just 11.3.0.