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There was an unexpected error in your org which is preventing this assessment check from completing: System.NullPointerException: Attempt to de-reference a null object

Hello,
I am studying for ADM 201 Cert using Trailhead.  When I login my Trailhead profile, it shows I have completed 8 badges.  However, when I click the link to show the 8 badges, it actually only shows 4 badges as logos on my profile.

Anybody know what many be the cause?  Thanks!

Hello, I am using "data import wizard" to import data in three custom objects named; candidates, positions and job applications. Job applications object has the master-detail relationships with "candidates" and "positions" objects. I am able to import candidate and positions data successfully thru CSV files but when I am trying to import data from job applications CSV, I am getting the error which is (INVALID_FIELD:Foreign key external ID: george@schnell.com not found for field First_Name__c in entity Candidate__c:--).

Candidate object has an email data type custom field which is enabled to get external data in the design but still I am getting above error. Job application CSV has three columns; namely "Email", "Position Title" and "Status". 

Can someone help?

It would appear that the method for importing custom objects via CSV is now different from what described in the force.com platform fundamentals guide.. or at least it is in my DE.

Specifically it would appear that it's not possible to use the email address as an external ID

How can one import the Job_Applications.csv file in a similar way?