Setting up a new C8 Pro that I purchased from Walmart under the seller "Hubitat Elevation". back in November. Read all the migration instructions and created a cloud backup on the C5 successfully on 2.4.0.143. Booted up my C8 Pro on version 2.3.7.146 and tried the restoring from the migration backup but got "Internal Error Occurred While Restoring Backup."
Tried a reboot and then upgraded the C8 Pro to try the migration again and this time got the same message but it broke down each failure and said that the database, zwave radio, zigbee radio, and file manager files all failed. I did see my devices and apps populated but no commands were working.
At this point, tried a soft reset in the diagnostics to try to get a cleaner slate to then try the migration again and still the same error.
Tried going to support.hubitat.com page but I don't see how to request support if I purchased from Walmart. Did I get a dud and should I go ahead and return the C8 Pro? I am powering the C8 using the included power brick.
While a soft reset and either a Z-Wave and Zigbee radio reset on the new hub or a retry of the migration containing these radios should basically do the same, you could also try a full reset (unregister the hub to make it easiest first). After doing this, you could further rule out the new hub being a "dud" by seeing if you can pair/include a spare Zigbee and Z-Wave device to the hub if you're fortunate enough to have any. This is rare but not impossible.
You could also retry the entire migration process, including re-capturing the backup on your existing C-5 hub. Note that a Z-Wave repair on a C-5 is recommended before capturing a backup, though that wouldn't explain any Zigbee problems.
Also, for Zigbee, what channel is your C-5 using (check Settings > Hub Details)? Some users have run into odd problems with channel 20, which is otherwise a great choice, so changing that and making sure everything works before trying the upgrade again might help with that side of things -- assuming this particular quirk would explain anything for you (only if you're using this channel, not everyone who is using this channel, and this wouldn't explain any Z-Wave problems).
Thanks for all the suggestions. It looks like I am on channel 20. I think I will try your other steps first before attempting to change the channel. Will report back soon.
If you do change the channel, it's not that scary. Most devices will reconnect on their own in an hour or two, often less, and those that don't (or that you don't want to wait for) can simply be re-paired (without removing them from the hub first). This would be much easier with functional Zigbee on the C-5 than down the road on the C-8 Pro if this ends up being a problem on that hub. (It's not for everyone--I'm on it myself!)
So I was able to get everything working by doing a full reset and then attempting the migration process again from a fresh backup created on the C5. I suspect the C8 being on the newer firmware this time resolved the issue. A suggestion for the Hubitat devs would be to have a software update be performed first before attempting any migrations or additional setup. Thanks for the help!
This should already be the case, and it definitely is for new hub setups (haven't tested the migration process in a while but think that would happen before you get here). In any case, glad it's resolved!
It doesn't happen when you click the option for restoring from a local or cloud backup. It went straight to the migration instead of allowing for a firmware update. If this was a brand new hub setup, that might be the case.
I had a very very similar experience. I was migrating from a C7 to C8 pro.. Followed all the migrations steps.. The C8 pro booted to '2.3.7.146'. It did not give me (or I didn't see an upgrade option) I performed the cloud backup migration. Afterwards I upgraded it to '2.4.0.148' none of my Zigbee devices worked. Apparently C8's have known zigbee issues.. I tried everything. Changing channels, Swapping the two antennas. Rebuild Zigbee network. Restore from backup. Turned off Hub for 30 minutes twice to force a zigbee panic, I could see the devices showing up in the device graph but I could not get anything to interact. My 90% of my lights have been left on the past 48 hours hoping they cured themselves. It wasn't until I saw this post mentioning a performing a full reset after the hub upgrade and then attempting the migration process. Now my devices are actually responding. Thanks @shiv81
Glad this post helped! I think the devs really need to add a step to update the new hub before performing a migration. This is sorely needed especially due to the issues on the older firmware.
Feels like a brand new hub should be forced to upgrade to the latest version (or at least give the user the option to) before the migration process is started Maybe that’s already the case with the newer firmware versions and it was just the earlier ones that wouldn’t do it. @bobbyD@gopher.ny
Most devices will reconnect on their own in an hour or two, often less, and those that don't (or that you don't want to wait for) can simply be re-paired (without removing them from the hub first). This would be much easier with functional Zigbee on the C-5 than down the road on the C-8 Pro if this ends up being a problem on that hub. (It's not for everyone--I'm on it myself!)
Maybe that’s already the case with the newer firmware versions and it was just the earlier ones that wouldn’t do it. 
