What happened to “Android Backup”?

There are PDF documents for the different platforms available where all backup options are explained in detail:

A data backup allows you to move your chats, groups, and contacts (including their verification level) to your new or reset phone. Moving data backups between devices is only possible within the same operating system. If you switch the OS (e.g., from iOS to Android), you can transfer your ID, contacts, groups, and privacy settings using Threema Safe. And you can always export chats.

Android

1. To create a data backup on your previous phone, select “Backups” in the main menu, and open the “Data Backup” tab.
2. In the “Backup Path” section, tap “Change,” and follow the on-screen instructions to define where the backup will be created on your device’s file system.
3. Tap the “Create data backup” button in the lower right corner.
4. Activate the option “Include media files.”
5. Once you have provided a password, Threema creates a backup in the folder you have chosen in step 2. This backup contains media files, contacts, chats, groups, and your ID.
6. Move the backup file to your new phone (by using a computer for instance).
7. Start Threema on your new phone. In the setup wizard, tap on “Restore from Backup,” and select “Data backup.”
8. Select your previously created backup and tap on “Restore.” After entering the valid password, your backup will be restored. Depending on its size, this can take several minutes.
9. Delete your ID on your old phone to make sure you receive notifications on the new device: n your old phone, navigate to “My profile,” and select “Delete ID.”

iOS

1. Create an ID export on your previous device: Tap on “Profile,” then select “ID export,” and activate the option “Include in phone backup” after exporting your ID. Make sure to store this password in a safe place; without it, you won’t be able to restore the exported ID.
2. Transfer your data using Quick Start from your old to the new device (or create an encrypted iTunes or computer backup of your old device, and restore it on your new device).
3. When starting Threema for the first time, tap “Restore from Backup,” select “Keep local data,” and tap “ID Export.” The ID-export string is prepopulated. What’s left to do for you is to enter the ID export’s password and to confirm by tapping “Done.”
4. Make sure your data was transferred correctly. If that’s the case, delete your ID on your old phone to make sure you receive notifications on the new device: on your old phone, open the “Profile” tab, and select “Remove ID and Data.”