Problems encountered when upgrading from 10.2.4 to 11.5.4

We upgraded the company bigip (Platform 3600) yesterday and we plan to upgrade from 10.2.4 to 11.5.4 but strictly follow the official documentation (https://support.f5.com/kb/en-us/products/big-ip_ltm /manuals/product/bigip-upgrade-active-standby-11-3-0/1.htmlunique_351099180) Upgrade step by step. We first upgraded from the backup machine, but after the upgrade was completed, the page was opened and the configuration file was missing, and there was a problem with the license. Are there good suggestions for upgrading? Thank you!