Cliff,
In my experience is better to start from a fresh start, even more if you are in R77.30. My process takes quite a downtime: what I would do is do a migrate export with the pre R80 migration tools (Make sure you save the used migration tools for later) and save the show configuration output to replicate it later.
After that perform a fresh install on the gateway with the latest ISO for R80.10, paste the show configuration output as needed and then perform the import with the previous used tools.
I recommend to test this process in a lab enviroment and verify that your export is working properly 🙂
Steps
1) Rollback preparation: Perform a backup, snapshot, and show configuration output of the current stand alone deployment and have the actual ISO
2) Download the export tools for Pre R80.10 from (Gaia Pre-R80.10 Migration tgz)
3) Unpack export tools on your current deployment and run the pre verifier tool, correct al errors, then perform the verifier again.
4) Perform export
5) Not mandatory but highly recommended: Create a lab with a standalone R80.10 and test import and if you are a maniac like me test the backup and snapshot of R77.30 from step 1.
6) Fresh install R80.10 in the 5400 gateway (Standalone)
7) Apply show configuration output as needed
😎 Unpack the same migration tools from step 2 into the new R80.10 gateway and perform import
9) Log in to SmartDashBoard and WebUI to check everything, install policy
Rollback
1) Fresh install previous version
2) Apply snapshot from initial setup or perform initial setup and apply backup
Hope it helps,
Regards