Is it safe to upgrade a stock 2018 C4 directly to current firmware?

[Rxich]

I have a 2018 C4, never used. Is it safe to directly upgrade to 2.3.3.122 from the 4 year old firmware?
@support @gopher.ny

[gopher.ny]

Since it's a never used hub, yeah, it should be safe. But it may get interesting
I'd suggest:

• Boot up the hub, minimal get started responses, update firmware.
• If update succeeds, update diagnostics tool using /hub/cloud/updateDiagnosticTool endpoint.
• If not, try running this from the command line:
  curl -X POST http://hubs.ip.address.here:8081/api/getLatest

[tomw]

I was in the same situation as @Rxich -- I had a never opened C-4 that I wanted to use.

In the off chance that a third person has something like this going on, here is what it took to get it working:

1. Connect Ethernet
2. Power up your hub
3. Navigate to http://hub_ip:8081/hubReset
4. Login with the last four digits of your MAC in ALL CAPS
5. Do a hard reset
6. Navigate to and login at: Hubitat User Portal
7. Register and update your hub and then wait a while
8. Once your hub is up and running, navigate to this address and then wait a while until it reports success: http://hub_ip/hub/cloud/updateDiagnosticTool

Thanks to @Mcgryf for blazing the trail with this and leaving some useful hints in another thread.

FYI @bobbyD