2006 - MySQL server has gone away

SELECT max(quantity) as qty FROM personal_offers_by_customers_status_1 WHERE products_id='5223' AND quantity<='1'

[XT SQL Error]

2006 - MySQL server has gone away

select count(*) as total from sessions where sesskey = '8ie4gin5st6no8f6pqcooo6a16'

[XT SQL Error]