Djurgården's team captain had to cancel last season in March due to injury.
Josefson suffered a concussion in January and missed the season's final 22 games.
Now the club announces that he will also miss the start of the coming season.
- "Josef" has regained symptoms from last year's injury.
Given last year's long convalescence, we do not expect Jacob in play for a long time to come.
First and foremost, it is now about Jacob getting back to everyday life without any symptoms, where rehabilitation is in focus, says Djurgården's sports director Joakim Eriksson.
Jacob Josefson played a match on Sunday in the Skoda Trophy against Linköping but was injured.
- As we have previously communicated, we are looking for further reinforcement for our forward side.
Given that Jacob and Manuel (Ågren) will not be available for play for a long time to come, and that we do not yet know what will happen to William Eklund and Alexander Holtz, we will intensify the search for additional players for the team building, says Djurgården's sports director Joakim Eriksson.