Signed IPSW files can be restored via iTunes. Unsigned IPSWs cannot currently be restored via iTunes.
✓ | iPadOS 15.5 (19F77) | 16th May 2022 | 5.85 GB | iPad_Spring_2021_15.5_19F77_Restore.ipsw |
✓ | iPadOS 15.4.1 (19E258) | 31st March 2022 | 5.83 GB | iPad_Spring_2021_15.4.1_19E258_Restore.ipsw |
✗ | iPadOS 15.4 (19E241) | 14th March 2022 | 5.82 GB | iPad_Spring_2021_15.4_19E241_Restore.ipsw |