Kobo Stack adds a cloud shelf, but the beta recovery warning comes first

Kobo Stack addresses a longstanding divide in an ebook library: books bought from a store tend to follow you between devices, while documents copied onto a reader often stay there. Kobo's new subscription adds cloud storage and synchronisation for personal files. On e-readers, however, it depends on the optional 6.0 beta, and that transition deserves as much attention as the new features.

The Stack support guide lists 50GB of storage, uploads through the website or a personal email address, and synchronised reading progress across supported Kobo devices and apps. Availability currently covers Australia, Canada, Ireland, Great Britain, New Zealand and Spain. This is a defined regional launch, not worldwide availability.

A cloud shelf for books you already have

Stack accepts PDF, EPUB and LCP-protected EPUB files, with a maximum of 200MB per file. The distinction matters: this is a service for bringing compatible personal documents into the Kobo ecosystem, rather than a promise to import any purchased ebook regardless of its protection or format.

Supported mobile versions are iOS 11.5 or later and Android 11.1 or later. The e-reader compatibility list names Libra Colour, Clara Colour and Clara BW, running beta software 6.0 or later. That list is more useful than assuming that every device bearing the Kobo name will gain the same functions.

The potential convenience is straightforward. A long PDF or independently purchased EPUB no longer has to be treated as a separate reading project on each supported device. But cloud convenience brings a subscription dependency that locally stored originals do not have. Kobo says cancellation ends synchronisation, leaves files in the account for 60 days and can lead to permanent deletion after that period. The service should not become the only place you keep an important document.

The beta has a specific recovery warning

Kobo's missing-content advisory documents a problem affecting some Libra Colour, Clara BW and Clara Colour readers after versions 5.18.270971 or 6.0.274403. Sideloaded books, reading statistics, vocabulary entries and annotations could disappear from view.

Version 6.0.276679 recovers books, statistics and My Words entries; Kobo also describes a subsequent 6.0.279225 update with further fixes. The advisory still distinguishes those recoveries from lost highlights and notes on sideloaded books, for which it says a fix is being developed. A general message that data can be recovered should not be read as confirmation that every annotation has already returned.

This warning changes the sensible response to an apparently empty library. Resetting a device is a familiar troubleshooting reflex, but here it can remove the very data an update might recover. The version number and the history of the device matter more than a generic recommendation to start afresh.

Free software changes remain separate from Stack

The 6.0 beta guide also describes changes that do not require the subscription, including multiple library cards through Libby and larger interface text. The new reading engine can alter pagination, while older stylus annotations may appear as a thumbnail showing the original marked-up page.

There are losses as well as additions. Kobo documents removed fast page-turning by holding a button, dropped RTF and HTML support, and problems with MOBI files. Someone whose library already works comfortably should weigh those changes before joining an optional beta simply to obtain a new cloud feature.

Stack's most persuasive promise is continuity: open the same personal book somewhere else without rebuilding your place in it. That promise becomes more credible when the local copy and its annotations remain safe. For this launch, checking compatibility and the recovery notes is part of understanding the product, not administrative work to do after pressing Update.