u-blox Memory Housekeeping Issue on XBee3 Cat M Cellular


u-blox has informed Digi of an issue for SARA-R410M-02B using previous firmware version L0. app version A.02.00. A new firmware release is available (L0. app version A.02.01) and is applied in u-blox production with first shipments beginning 21 Dec 2018. The following guidelines and recommended actions are applicable to affected fielded product using previous firmware version (L0. app version A.02.00.)

This u-blox module is a component in the Digi XBee3 LTE-M/NB-IoT Cellular Smart Modem (XB3-C-A2-UT-001). 

The issue can cause memory corruption which renders the u-blox cellular component unusable. 

This issue can occur when a device is put to sleep or power cycled within 20 seconds of a scheduled memory maintenance procedure. The memory maintenance procedure occurs every 124 days after the first network registration of the device. 

Devices that do not sleep and do not periodically power cycle have a low risk of occurrence.  

Affected Products

This issue affects the following Digi products: 

  • XB3-C-A2-UT-001 - Digi XBee3 Cellular Smart Modem, LTE-M/NB-IoT
  • XK3-C-A2-UT-U - Digi XBee3 Cellular Smart Modem, LTE-M, AT&T
  • XK3-C-N1-UT-E - Digi XBee3 Cellular Smart Modem, NB-IoT Development Kit

Customer Resolution


To reduce the risk of this issue occurring on devices that have not been patched, configure your application to wait at least 30 seconds after network registration before going to sleep or performing a power reset. This is a risk-reduction step and is not a substitute for patching u-blox firmware. 

Firmware Update Options: 

1.  USB Direct
Update u-blox firmware over USB direct mode with the u-blox EasyFlash Firmware Download Tool. u-blox firmware application version should be updated to A.02.01. You can find a link to the update instructions on the 
product support page under "Firmware Updates" (select u-blox A.02.01 EasyFlash Update)

2.  UART

Digi will make Firmware Over AT (FOAT) patching and is targeted for release in June 2019. This option will work in XCTU and host processor. 

3.      Firmware Over-The-Air (cellular)

Digi will make Firmware Over-The-Air (FOTA) patching and is targeted for release in June 2019. 


Product that has already encountered this failure mode should be returned to Digi through the normal RMA process.

Last updated: May 08, 2019

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