```ruby
class AssociateProversWithOntologyVersions < ActiveRecord::Migration
  def self.up
    OntologyVersion.find_each do |ontology_version|
      retry_provers_retrieval(ontology_version, 3)
    end
  end

  def self.down
    OntologyVersion.find_each do |ontology_version|
      ontology_version.provers = []
      ontology_version.save!
    end
  end

  protected

  def self.retry_provers_retrieval(ontology_version, max_attempts)
    ontology_version.retrieve_available_provers
  rescue Net::ReadTimeout
    if max_attempts > 0
      puts "Timeout, trying again: OntologyVersion #{ontology_version.id}"
      retry_provers_retrieval(ontology_version, max_attempts - 1)
    else
      puts "Timeout, limit reached: OntologyVersion #{ontology_version.id}"
    end
  rescue ::StandardError => e
    puts "Errored at OntologyVersion #{ontology_version.id}"
  end
end
```

Print error messages on stderr.
user
```ruby
class AssociateProversWithOntologyVersions < ActiveRecord::Migration
  def self.up
    OntologyVersion.find_each do |ontology_version|
      retry_provers_retrieval(ontology_version, 3)
    end
  end

  def self.down
    OntologyVersion.find_each do |ontology_version|
      ontology_version.provers = []
      ontology_version.save!
    end
  end

  protected

  def self.retry_provers_retrieval(ontology_version, max_attempts)
    ontology_version.retrieve_available_provers
  rescue Net::ReadTimeout
    if max_attempts > 0
      $stderr.puts "Timeout, trying again: OntologyVersion #{ontology_version.id}"
      retry_provers_retrieval(ontology_version, max_attempts - 1)
    else
      $stderr.puts "Timeout, limit reached: OntologyVersion #{ontology_version.id}"
    end
  rescue ::StandardError => e
    $stderr.puts "Errored at OntologyVersion #{ontology_version.id}"
  end
end
```
assistant