Many users are now learning what happens when Duolingo clumsily updates your course — something that made me stop using the app months ago.

Duolingo users online say the recent course upgrade has disrupted their progress, leaving some lessons feeling out of order.

Duolingo’s stable of languages expanded today to include Arabic — both the spoken and written word. With this, Duolingo now teaches five of the world’s most common tongues, and TNW got the chance to ...