As the error was accomplished through the god Indra, he grants Hanuman a want that his entire body could be as solid as Indra's Vajra, Which his Vajra also can not harm him. Together with Indra other gods have also granted him wishes: the God Agni granted Hanuman a desire https://card-directory.com/listings625000/the-2-minute-rule-for-panchmukhi-hanuman