While upgrading ACX1000 in customer network from version 12 to 19, it always failed to upgrade and came up with old version after reboot.

This document helps in resolving this issue.

• md5 for the new image is matching correctly.
• New version is verified without any issues.
• After upgrade device is up with old version 12.2 and installed version shows as 19.3

Model: acx1000

JUNOS Base OS boot [12.2R1.3]

JUNOS Base OS Software Suite [12.2R1.3]

JUNOS Kernel Software Suite [12.2R1.3]

JUNOS Packet Forwarding Engine Support (ACX) [12.2R1.3]

JUNOS Online Documentation [12.2R1.3]

JUNOS Routing Software Suite [12.2R1.3]

JUNOS Installation Software [19.3R3.6]

Device entered into loader propmpt while rebooting, thus installation of new image is failed.

From console logs:

Hit [Enter] to boot immediately, or space bar for command prompt.





Type '?' for a list of commands, 'help' for more detailed help.

loader>  

loader> Bus Fault @ 0x00000001, fixup 0x00000000

Machine check in kernel mode.

Caused by (from msr): regs 00044b20 Unknown values in msr

NIP: 00000001 XER: 00000000 LR: 0FFB151C REGS: 00044b20 TRAP: 0200 DAR: 00000001

MSR: 00000001 EE: 0 PR: 0 FP: 0 ME: 0 IR/DR: 00



GPR00: 00000060 00044C10 00000200 F7F04500 00000100 00000018 0003F3C8 0004856C 

GPR08: 000605E0 00000000 000605C8 0FFB1530 44000088 00000000 0FFE4600 10020000 

GPR16: 00000000 00000000 00000000 00000000 00000000 0FE9DED8 0FEA0440 00000000 

GPR24: 0FEA04D8 00000000 00000100 00044C98 00040000 0FE9DF84 0FFE4EE0 0004665C 

Call backtrace: 

00000000 00038024 0FFB1544 000299D0 000132D4 00036174 00014B90 

0001A540 0FFBBB78 

machine check

### ERROR ### Please RESET the board ###

I2C:  ready

Suspected console port is causing the interrupts.

In secure-crt, anti-idle option was set which was sending space after set interval.

Thus space was getting added after prompt - "Hit [Enter] to boot immediately, or space bar for command prompt."

After disabling this setting in secure-crt, router was successfully upgraded with the new version.

Also removal of console cable will help in this scenario.