I finally got a chance to downgrade and migrate. Everything is working well (Zwave, ZigBee, all rules and apps including the API to connect with Home Assistant).
Just to see if it would work, I didn't remove any custom device drivers, I didn't deactivate any apps and I only downgraded the C5 to 2.3.5.152 (the C8 is running 2.3.6). For me it wasn't necessary to downgrade both to migrate.
Far from a smooth migration process but I appreciate the support from the community.
Update: I wrote this too soon, multiple zigbee devices worked immediately after migration but dropped off shortly afterwards. Specifically some Hue motion sensors and Aqara contact sensors. Interestingly, some Hue motion sensors and Aqara contact sensors are working fine others reported a couple of times after migration then dropped off....These were rock solid on the C5. I've rebooted the Zigbee radio and will go around and repair everything when I get some time.
I downgraded to platform 2.3.5.146 that was stored on my C-5 and the "Internal error occurred".
so mark one down for the downgrade migration FAIL column using a downgraded platform on a C-5 method.
C-8 came with 2.3.6. I'll try downgrading the C8 next so both are on 2.3.5 and retry.
update: I downgraded the C-8 now 2.3.6.144—> 2.3.5.152. Migration succeeded this time. So seems the problem is with the C-8 running 2.3.6 as well.
I downgraded tonight to 2.3.5, didn't disable any apps, backed up to cloud, clicked the migrate on the c-8 and was successful. Thanks everyone for making this happen.
Sorry that only the C5 downgrade didn't work for you @alex1. I wonder if the version of 2.3.5 is important? I downgraded my C5 to 2.3.5.152 and I noticed that you started from 2.3.5.146. Hopefully, a new version of 2.3.6 will be released soon to avoid this issue!
It might be possible that 2.3.5.146 vs 2.3.5.152 may make a difference. However, it's also possible that the downgrade of the C-8 from 2.3.6.144—> 2.3.5.152 fixed something as well. Sounds like the root cause was found, maybe we will get a hint of the root cause in the release notes for 2.3.7.
I can tell you the root cause if you'd like. The cloud backup process for C-5 post 2.3.5 is broken for Z-Wave and the C-8 restore notification pre 2.3.7 is misleading. The "internal error" should say partial restore completed. Both have been fixed in the latest release.
Hello @bobbyD can you please let me know if this issue is fixed in 2.3.7 ?
I tried to migrate yesterday from C5 to C8 and I'm getting the "Internal error" issue when migrating on the C8.
Can you please let me know if fix deployed with 2.3.7 is solving the migration issue ?
If so, how can I get support facing this "Internal error" when migrating from C5 to C8 ?
Yes the migration issues were supposed to be fixed in 2.3.7
Do you have both the Zigbee and Z-Wave radios enabled on both the C5 and C8? I think if the radios are shut off it can cause issues with the migration.
When you take the backup on the C5 do you get any sort of backup errors?
If you are not getting sufficient support here you could put in a warranty claim on their support site: https://support.hubitat.com/
Thanks @jtp10181
Old C5 is turned off during the migration
New C8 is out of the box (or soft reset).
I'm always getting the same "Internal Error" message when migrating from cloud backup.
I'm Hub Protect + Remote admin subscriber
I've logged a ticket to Hubitat team on Support site
You did not answer any of my questions. Are the Zigbee and Z-Wave radios enabled on the C5 before you took the cloud backup? Not the hub itself being on, but in the details pages for both Zigbee and Z-wave, the radios need to be enabled even if you are not using them.
When you take a cloud backup on the C5 do you get any errors?
Also, are both hubs updated to 2.3.7 platform? I think it is most important for the C5 to be updated, since the issue that got fixed was occurring during the backup (leading to an error on the restore).
I understand the "Internal error" comes from the C8 when trying to load the backup, but this may be due to a bad backup from the C5 to begin with.