Constraint mongo@1.1.5

Hello,
I am trying to migrate a project for which I do not know the version of meteor to meteor 3.1.2
When starting meteor I get the following error:

While selecting package versions:
error: Conflict: Constraint mongo@1.1.5 is not satisfied by mongo 2.1.0.
Constraints on package “mongo”:

  • mongo@2.1.0 ← top level
  • mongo@~2.1.0 ← top level
  • mongo@2.0.0 ← reactive-dict 1.3.2 ← session 1.2.2
  • mongo@1.1.5 ← littledata:synced-cron 1.5.1

Can someone tell me how to solve this problem
Thank you very much
YC