What is the difference between a Threema ID and an ID backup?
To restore a Threema ID, you need an ID backup (or a Threema Safe backup). It consists of 80 digits and letters in groups of four characters (separated with dashes). You will get this string in two formats after creating an ID backup: as plain text for copying/pasting, and as a QR code.
In the restore menu, you can either enter the long string manually, or you can scan the QR code. Restoration is only possible with an ID backup. If you mistakenly scan a public Threema ID, you will see a long string after scanning that starts with “3mid:”. Restoration will not be successful in that case. Please ensure that you are using an ID backup for restoration.