Backups don't work after de-registering an account during migration

No source file or test is named. Start with the Android device-transfer flow and backup behavior after deregistration, then compare them with the linked Backup and Restore and Troubleshooting Device Transfers guides. Done means the requested fallback behavior or the missing troubleshooting guidance is clearly addressed and verified for the migration state described.

Guidelines

• I have searched open and closed issues for duplicates
• I am submitting a bug report for existing functionality that does not work as intended
• This isn't a feature request or a discussion topic

Bug description

(I hope this is not a feature request. I apologize if it is!)

During migrating from my previous Pixel 9 Pro to a 11 Pro, I followed the obvious path in the apps, also according https://support.signal.org/hc/en-us/articles/360007059752-Backup-and-Restore-Messages#android_restore

Device next to each other, WiFi on, no firewalls/VPNs/hotspots, charging, unlocked, latest Android and latest App, BlueTooth on, WiFi Direct enabled, the works.

However, the devices wouldn't find each other - both kept scanning, regardless of how often I'd restart the process. I was getting quite devastated at this point, since, uh, I didn't have working backups (I fumbled that step).

So I wanted to fall back to taking a backup and moving that over instead. But the old device no longer allowed this (because at that point, the account is already deregistered, even if all messages are still visible).

Step 8. at https://support.signal.org/hc/en-us/articles/10075160307482-Troubleshooting-Device-Transfers states that "Backups are optional but recommended" but also "Enable Secure Backups before or after transferring" (on re-read, I realize this step probably meant after *successful transfer).

So my suggestion here would be to allow backups to be taken at this point again, in case the direct transfer doesn't work. Seeing data you can't rescue is quite painful :-)

In my personal scenario, while I followed the guide - disabled VPN, no Wi-Fi Hotspot - to not interfere with Wi-Fi Direct (and I had the devices paired on Wi-Fi Direct as far as Android thought). What I actually ended up having to do was to fully disconnect from my local WiFi (even though it doesn't impose any firewalls between the devices).

That step ("Disconnect from any WiFi network") isn't in the debugging list, so maybe adding that would be helpful?

So I lucked out, and I'll fix my backup process for sure. But I feel the guide or process could have offered two steps that'd have helped me.

Screenshots

No response

Device

Pixel 11 Pro, Pixel 9 Pro

Android version

Android 17

Signal version

8.23.3

Link to debug log

https://debuglogs.org/android/8.23.3/337e2c4f10b0272c88b679fb9ff388d5311a8e789aa60243e09958df3ba27149 from the new device.

Incidentally, I cannot get the debug logs from the old device. Because that's now in "Complete registration on your new device" mode, and I can either click "Done" which immediately closes the app - or "Cancel and activate this device", which I don't want to risk right now given that the migration has finally succeeded.