The company has no plans to undo the changes.
In the previous version of Duolingo, users worked through a series of lessons, where completing one unit would open other lessons.
In the new version of Duolingo, the company has eliminated the ability to choose which new lesson to take next.
The backlash against Duolingo has been particularly harsh.
Some users have even taken to campaigning against the update, attempting to get the company’s attention with one-star online reviews.
The backlash also highlights just how successful Duolingo has become. The app, which is free to use, says it has built up a user base of more than 500 million people.