As the error was accomplished through the god Indra, he grants Hanuman a desire that his entire body would be as solid as Indra's Vajra, and that his Vajra can also not hurt him. In conjunction with Indra other gods have also granted him wishes: the God Agni granted Hanuman https://baglamukhivashikaranmantr37159.tinyblogging.com/the-ultimate-guide-to-hanuman-80729279