Neo4j Administration course, Part 4, Exercise 3, Step 2, when executing ./testRead.sh bolt 11687 I got the above error. I found the solution:
Need to make sure the passwords for core1, core2, and core3 databases matches the password in the four .java files in the testApps folder, which by default is "training-helps" -- I don't think it was clear in the earlier part of the exercise where we change our password that we needed our passwords to be this particular password.
Just putting this out there in case anyone else gets stuck at the same place I did.