See: Bulgaria urged to stop locking up stateless people by detained heart doctor (Thomson Reuters Foundation, link):
“Sager Al-Anezi, who is from a large stateless population in Kuwait called the Bidoon, qualified as a doctor after moving to Bulgaria in 2007 and was training to become a heart surgeon.
The doctor said stateless people could not go to university in Kuwait, but he was able to obtain a passport from a third country – which he did not want to name – with Kuwait’s blessing which allowed him to study abroad and led him to Bulgaria.
But when he tried to renew that passport the third country refused and he applied for formal recognition as a stateless person in Bulgaria. He was locked up on Jan. 3 when he chased up on that application.”