This article discusses changes to the Bluetooth SDK version 2.7.0.
Starting in SDK version 2.7.x, the so-called legacy bootloader has been deprecated. This means that if you build and flash one of our sample applications you must now also build and flash a bootloader. The most reliable method is to build a bootloader for your device using the Appbuilder and flash the combined bootloader (*-combined.s37) using Simplicity Commander. This ensures that your device has both stages of the bootloader and will allow your application to run.
If your device does not have a bootloader, the symptoms you can expect include the application failing to start and the debugger showing the message "failed to read memory" in the disassembly window.
Please see UG266 for detailed information on the Gecko bootloader.
Right on, I must have erased the bootloader without paying too much attention and so I was expecting flashing the hex file as usual to work.
I see the new SDK release, where can I find the change log?
For BGM111 you will normally pick UART DFU if you are using NCP mode or in-place OTA if using SoC mode.
For more info on this please refer to UG266 and AN1086.