Xteink, makers of credit card-sized e-readers, have suddenly blocked their devices from running third-party firmware in certain regions, leaving users with a less polished user experience.

The move comes after several users reported crashes and other issues following the installation of alternative software. Xteink claims these problems are safety concerns, but some argue it's a step towards limiting user freedom.

In a statement, Xteink explained that recently shipped devices now come with firmware flashing disabled to prevent future issues. However, for those who purchased their e-readers through the company’s official website, there is no restriction on using third-party software.

The controversy highlights the ongoing debate between tech companies and users over control of device functionality. It also raises questions about how far firms will go to maintain market share in a crowded e-reader space.

Despite this setback, Xteink's devices remain popular, with the X4 making it onto Amazon’s best-seller list thanks in part to its CrossPoint Reader software, which offers a more refined reading experience than some of its competitors.