Tawus and Amr bin Dinar (may Allah have mercy on them both) narrate from Ibn Abbas (may Allah be pleased with him) that there is no prevention except prevention by an enemy. One of the two added: Prevention has now come to an end.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10091
The saying of Allah Almighty: "And complete the Hajj and Umrah for Allah. But if you are prevented, then (offer) whatever sacrificial animal is easily available." (the verse) [Surah al-Baqarah: 196]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10091