Last b-tree level at level <num> had non-null next pointer.
  Last b-tree node points to logical dbkey <num>:<num>:<num>.

  Explanation:   An  index  verification  error  was  found   when
  verifying  the  next  b-tree  node  of  a b-tree node.  The next
  b-tree node of a b-tree node B at level L is the  next  level  L
  node on the right of b-tree node B.  The rightmost node at level
  L should point to the NULL dbkey.  In this case it pointed to  a
  different dbkey.