https://devzone.nordicsemi.com/f/nordic-q-a/126877/upgrading-soft-device-over-otaHi, We have products in the field using SDK 15.2 with its associated S140 SoftDevice s140_nrf52_6.1.0_softdevice, and bootloader. We are upgrading our application to SDK 17.1.0 with its associated S140 SoftDevice s140_nrf52_7.2.0_softdevice. Canen-USTelligent Community 13Thu, 05 Feb 2026 14:07:41 GMThttps://devzone.nordicsemi.com/thread/560450?ContentTypeID=1Thu, 05 Feb 2026 14:07:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a44e08d7-27f4-43dc-b898-be80a9d803b3Turbo J<p>You can OTA softdevice, but only combined with a new bootloader together. Keep in mind that the bootloader requires its specific softdevice to work properly.</p> <p>If you had enough flash space left, you could also try an NCS SDK based app and keep the old SD on. Could work if you ran BT in either peripherial or central mode exclusively, as this reduces flash space requirements.</p><div style="clear:both;"></div>