Device not going to DFU mode on some devices

[vishnu3391_uh]

Hi,

We are currently stuck with a big issue on as we are not able to update the devices(nRF52840) on field. We have changed the clock source to internal in the last released build. But we changed the settings only in the application and released only an application update. Now when we tried to release a new application many users are not able to update to the new version and we found that they are getting DFU error. Upon searching the devzone we found we should've updated the bootloader also with the same clock settings change as in application. More than 10k devices were able to update to the new version. 
Does this says that those devices which were failing has external clock accuracy issue? Why is it failing on certain devices and not on other devices? How to fix this issue? 

Also we changed the softdevice version to v7.3 and same like above we didn't change this in bootloader. What is the proper and best way to update SD and bootloader update in this scenarios. Considering the devices on field has bootloader with external clock and application with internal clock and the SD version 7.2. What is the proper DFU package file making process here to update Bootloader+SD+application?

Thanks,

Vishnu

[Vidar Berg]

Hi Vishnu,

I don't think the different clock source configuration explains the DFU failure.The new clock configuration will not take effect until after the update is complete. Are you able to provide more information about when and where the DFU process is failing? Is the failure happening when attempting to enter DFU mode, or does it happen at some point during the firmware transfer? Also, do you have any data to check if the failure might be specific to certain phone models?

What is the proper and best way to update SD and bootloader update in this scenarios.

You can make a distribution packet that contains the SD+BL and application.

Best regards,

Vidar

[vishnu3391_uh]

Vidar Berg said:

You can make a distribution packet that contains the SD+BL and application.

Vidar Berg Regarding this. In both application and bootloader we were using s140 7.2. Now updating to 7.3.
Should we need to build bootloader with updated softdevice and then create the package with new bootloader+ 7.3 SD + new application with 7.3 support. Will the existing bootloader with 7.2 SD accepts new package? Anything needs to change?. 

Thanks,

Vishnu