So it seems the backup file was somehow incomplete. Not sure if it happened when I created it or when I moved it to a thumb drive.
New file worked.
The error I posted was from my iPhone iOS 26
But my backup iPad iOS 18 wasn’t working either.
The backup was created on my iPad M2 also iPadOS 18.
Strange but it’s fine now
Thanks for your messages
The file is nearly 30GB is size. I have almost 550 tracks self made all in multitracks.
For the iOS 26 update I will briefly test my iPhone today at the gig during sound check and report if it works fine. I think it should