Does the prayer of one with bare shoulders become invalid?

The Shaykh : No, rather he must cover the 'awrah (part of the body that must be covered) related to the prayer, if I may express it that way. This is based on the saying of the Messenger of Allah (peace and blessings be upon him): Therefore, Imam Ahmad explicitly stated that if a person prays with his shoulders bare, his prayer is invalid. This is the truth by which we declare our faith in Allah, due to this authentic hadith: .
Since the general command to adorn oneself for prayer is established, and it is established that it is the custom of Muslims to cover the head rather than leave it bare, we believe that praying with a bare head is disliked (makruh). This is not because there is a specific prohibition, but because it contradicts the customs that Muslims have followed.
On this occasion, and as a conclusion to the answer, I am pleased with what Shaykh al-Islam Ibn Taymiyyah (may Allah have mercy on him) mentioned regarding the hijab (covering prescribed for women) and clothing of a woman in prayer. It is a small treatise, perhaps you have come across it. There he mentioned a narration that Ibn 'Umar (may Allah be pleased with him and his father) saw his slave Nafi' praying with his head bare. He said to him: "Do you think that if you went to meet one of these princes, you would meet him with your head bare?" He said: "No." He said: "Allah is more worthy of being adorned for."
other than that