Field Notice: FN74400 - Some Cisco Network Convergence System 540 Series Routers Will Exhibit Continuous Boot Loop During Upgrade to Cisco IOS XR Software Release 26.1.1 or Later - Software Upgrade Recommended

Some Cisco Network Convergence System (NCS) 540 Series Routers will exhibit continuous boot loop while they are being upgraded from any Cisco IOS XR Software release earlier than Release 25.4.1 to Release 26.1.1 or later, except when the upgrade is performed from Release 25.4.1. The affected devices will abort the software upgrade process. 

Routers with affected product IDs (PIDs) have a compatibility issue between the Universal Boot Loader (U-Boot) and the Cisco IOS XR Software release. Two feasible solutions are provided in the Workaround/Solution section of this field notice.

When affected routers are upgraded to Cisco IOS XR Software Release 26.1.1 or later, they will exhibit the following output in the console:

Booting /EFI/BOOT/bootaarch64.efi
Successfully verified signature on the image
Signer certificate chain verified successfully
error: no such device: ((cd0)/EFI/BOOT)/EFI/BOOT/grub.cfg.
Verifying (cd0)/EFI/BOOT/grub.cfg...
Successfully verified signature on the image
Signature verified
Signer certificate chain verified successfully
(cd0)/EFI/BOOT/grub.cfg verified using Pkcs7 signature.
Verifying (cd0)/EFI/BOOT/grub.cfg...
Successfully verified signature on the image
Signature verified
Signer certificate chain verified successfully
(cd0)/EFI/BOOT/grub.cfg verified using Pkcs7 signature.
error: serial port `com0' isn't found.


  Booting `Install IOS-XR'


Booting from ISO image..
Loading Kernel..
Verifying /boot/Image...
Successfully verified signature on the image
Signer certificate chain verified successfully
/boot/Image verified using attached signature.
alloc magic is broken at 0x94f4bf80: 6c616d7265687420
Aborted. Press any key to exit.

Solution 1:

The upgrade process for affected Cisco NCS 540 Routers to Cisco IOS XR Software Release 26.1.1 requires an interim upgrade to Release 25.4.1, which includes an upgrade to the U-Boot version. The field programmable device (FPD) auto-upgrade feature needs to be enabled for this solution. The supported upgrade path for Release 26.1.1 is as follows:

1. Ensure that the FPD auto-upgrade feature is enabled.
2. Perform an initial upgrade from the current base release to Cisco IOS XR Software Release 25.4.1. This upgrade will update the primary bootloader (U-Boot) to Version 21.04.
3. Verify that the Prim-Bootloader has been upgraded to Version 21.04 using the show hw-module fpd command.
4. Proceed with the second system upgrade to Cisco IOS XR Software Release 26.1.1 or later.

Solution 2:

Before upgrading an affected router to Cisco IOS XR Software Release 26.1.1 or later, use the following steps to install the SMU:

1. Enable the FPD auto-upgrade feature before activating the SMU.
2. Install and activate the bridge SMU, which triggers a reload and upgrades U-Boot to Version 21.04. The SMU for various Cisco IOS XR releases and instructions are provided in the following table.
3. Verify the Prim-Bootloader has been upgraded to Version 21.04 using the show hw-module fpd command.
4. Proceed with the system upgrade to Cisco IOS XR Software Release 26.1.1 or later.

The router can be recovered to previous releases through preboot execution environment (PXE) or USB boot.

Cisco does not recommend Return Materials Authorization (RMA) for the issue described in this field notice. The provided solution will resume the router to normal operation.