Festival story · 2 tellings · North India, Pan-India
The night the prison opened (Krishna's birth)
Warned that Devaki's eighth child will kill him, Kamsa imprisons her and Vasudeva and kills their sons. The eighth is born at midnight; the chains fall, Vasudeva carries him across the flooded Yamuna to Gokul and brings back Yashoda's daughter, who escapes Kamsa and rises as the Goddess. The Harivamsha has Vishnu send the goddess Nidra to be born that night.
A voice at Devaki's wedding warns Kamsa that her eighth child will kill him. Vasudeva promises to hand over every child; Kamsa imprisons them and kills six sons, and the seventh is moved to Rohini's womb. The eighth is born at midnight on Bhadrapada krishna ashtami, four-armed, then becomes a baby. The guards sleep, the chains fall, the doors open; Vasudeva carries him across the flooded Yamuna under Shesha's hoods to Nanda's house and brings back Yashoda's newborn daughter. Kamsa tries to dash her on a stone; she rises as the eight-armed Goddess and tells him his killer lives.
Before his birth Vishnu goes to Patala and asks Nidra, the goddess of sleep, to be born to Yashoda on the same night. He promises that she will escape Kamsa, become Indra's sister, live on the Vindhya mountains and kill Shumbha and Nishumbha. She puts the guards and Gokul to sleep for the exchange, and when Kamsa dashes her on a rock she rises unharmed and becomes Vindhyavasini.
What is different here:
Vishnu and Nidra plan the night beforehand; the girl becomes the goddess of the Vindhyas.
Sources: Bhagavata Purana 10.1 to 10.4, the birth of Krishna (English translation, Vedabase); Harivamsha, Vishnu Parva 2 to 4 (translation of M. N. Dutt, 1897)