Similar to this issue I think, but triggered when performing a query on entities modelled with Class Table Inheritance, e.g.

$qb = $repository->createQueryBuilder('entity');
$metadata = $em->getClassMetadata($class);
$qb->where('entity INSTANCE OF :type')->setParameter('type', $metadata);
$qb->getQuery()->execute();

Seems that there isn't a corresponding entry in the parameter mapping array for this clause, which triggers the exception at line 254 of Doctrine\ORM\Query:

if (count($paramMappings) != count($this->parameters))