Ackerman – who has made five appearances for Dragons RFC this season – sustained a fractured tibia and fibula in the Under-20 Six Nations fixture with France at Cardiff Arms Park on last night.
The 19-year-old underwent surgery on Friday afternoon and now begins his rehabilitation and recovery journey.
Dragons head coach Dai Flanagan said: “Harri has been playing exceptionally well, for Dragons and Wales this season, so it’s a blow to lose him in this manner.
“Harri has led Wales Under-20s superbly during this Six Nations so it’s disappointing that he’s been deprived of finishing the international season and the rest of our domestic campaign.
“We’re pleased to report that surgery has been successful, and he has our full support as he commences his return to fitness.
“I know our fans, and supporters right across Welsh rugby as a whole, will join us in sending him our very best wishes.”
