i am getting the following error while checking the challenge
"Challenge Not yet complete... here's what's wrong: 
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"
below is my code:
public class AccountHandler{
    
    public static Account insertNewAccount(String strName)
    {
        if(strName!=null)
        {
            
       
        Account acc=new Account(Name=strName);
        try
        {
            insert acc;
            return acc;
        }
        catch(DmlException e)
        {
            System.debug('Dml exception has occured' +e.getMessage());
            return (null);
        }
        }
        else
        {
            return null;
        }
    }
}

 i ahve completed all the steps which are required for data import challenge but when i am clicking on Check Challenge,i am getting this error "Challenge Not yet complete... here's what's wrong: 
All the contact records from the CSV file were not found in the Org."

I have completed all steps required for challenge but when i am clicking on Check Challenge ,getting this error
"Challenge Not yet complete... here's what's wrong: 
Could not find a dashboard with a name 'Adoption Features'."

i am getting the following error while checking the challenge
"Challenge Not yet complete... here's what's wrong: 
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"
below is my code:
public class AccountHandler{
    
    public static Account insertNewAccount(String strName)
    {
        if(strName!=null)
        {
            
       
        Account acc=new Account(Name=strName);
        try
        {
            insert acc;
            return acc;
        }
        catch(DmlException e)
        {
            System.debug('Dml exception has occured' +e.getMessage());
            return (null);
        }
        }
        else
        {
            return null;
        }
    }
}

I have completed all steps required for challenge but when i am clicking on Check Challenge ,getting this error
"Challenge Not yet complete... here's what's wrong: 
Could not find a dashboard with a name 'Adoption Features'."