I get the following error (dump MongoDB 3.2) (restore MongoDB 3.4):
Failed: ngivr-dev.ledgerhelpers: error creating indexes for ngivr-dev.ledgerhelpers: **cr
safe=true is not an index specification.
In previous versions of MongoDB, lower than 3.4, extra indexes specifications can be added. Those were used by specific drivers.
In 3.4, mongodb added a validation on indexes specification:
Ensuring that the specified index options are valid. Previous versions ignored invalid options.
That's why you have this error. I am afraid you need to ensure that the index in your 3.2 version does not have invalid index specificaitons, and after that do the mongodump.
As kz_sergey says in his answer, you can mongorestore using --noIndexRestore, that should work fine.