Apple is facing a class action lawsuit over the design of its MacBook and MacBook Pro keyboards which, consumers complain, has keys that are prone to becoming stuck.

The lawsuit follows a litany of complaints across user forums, specialist mediaand a petition with over 21,000 signatures urging Apple to recall the Mac laptops released since late 2016.

“Because of the new keyboard design, consumers report that fixing affected keys requires replacing the whole keyboard, which costs $700,” Girard Gibbs, counsel for the plaintiffs, state. “Because typing is the primary purpose of laptops, over time, consumers have become more and more frustrated with the keyboard defect.”

In 2015 Apple introduced a new key switch mechanism that allowed it to produce a keyboard much thinner and with a smaller amount of travel. It was first used on the 12in MacBook laptop, and then later on the redesigned MacBook Pro line from late 2016.

The “butterfly” mechanism replaced the older “scissor” mechanism, which is still used by the majority of laptop keyboards, and was intended to make the keys more stable and responsive when pressed.

But the plaintiffs claim the redesign has resulted in a defective product: “Apple’s butterfly keyboard and MacBook are produced and assembled in such a way that when minimal amounts of dust or debris accumulate under or around a key, keystrokes fail to register.”

As typing is the keyboard’s primary input for the laptops, the plaintiffs argue that when a keys become stuck on the MacBook or MacBook Pro the machines, which cost upwards of £1,249, become “unsuitable for its ordinary and intended use”.

The lawsuit argues that “Apple has failed to disclose that the keyboard is defective, and this information would have been important to Plaintiffs’ decision to purchase a MacBook” and that even after repair the problem reoccurs.

Clearing dust and debris out of the keyboard is difficult. Apple has a guide on how to clean a MacBook or MacBook Pro keyboard with compressed air, but further treatment requires repair by technicians.

Apple did not immediately comment.