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Downgrade IOS from 15.0(2)SE6 to 12.2(55)SE7 issues

I received 2x 2960PCL switches that were shipped with IOS 15.0(2)SE6. I have attempted to downgrade these switches to 12.2(55)SE7 without success. So far I have pushed the 12.2 image to the switch via xmodem. When trying to boot from the image the switch installs and executes the image then spits out the following:

File "flash:c2960-lanbasek9-mz.122-55.SE9.bin" uncompressed and installed, entry point: 0x3000

 : Unexpected exception to CPUvector 1100, PC = 6280A8
-Traceback= 6280A8 65813C 14CBA08 152D28C 352C

 : Unexpected exception to CPUvector 0, PC = 6280A8
-Traceback= 6280A8 15344F0 A30748

Nested write_crashinfo call (2 times)

It then loops:

 : Unexpected exception to CPUvector 0, PC = 6280A8
-Traceback= 6280A8 15344F0 A30748

I have formatted the flash and repeated the process with the same results. Any help would be appreciated.


Frequent Contributor

please copy paste heresh

please copy paste here

sh ver

sh inv



Switch#show verCisco IOS

Switch#show ver
Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 15.0(2)SE6, RELEASE SOFTWARE (fc2)
Technical Support:
Copyright (c) 1986-2014 by Cisco Systems, Inc.
Compiled Wed 09-Apr-14 03:40 by prod_rel_team

ROM: Bootstrap program is C2960 boot loader
BOOTLDR: C2960 Boot Loader (C2960-HBOOT-M) Version 15.0(2r)EZ1, RELEASE SOFTWARE (fc2)

Switch uptime is 1 minute
System returned to ROM by power-on
System image file is "flash:/c2960-lanbasek9-mz.150-2.SE6.bin"

This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

If you require further assistance please contact us by sending email to

cisco WS-C2960+24PC-L (PowerPC405) processor (revision B0) with 131072K bytes of memory.
Processor board ID FCW1816B1WV
Last reset from power-on
1 Virtual Ethernet interface
24 FastEthernet interfaces
2 Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.

64K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address       : 28:C7:CE:E2:9B:80
Motherboard assembly number     : 73-15618-01
Power supply part number        : 341-0266-03
Motherboard serial number       : FOC18159K1Z
Power supply serial number      : DCA1813H04W
Model revision number           : B0
Motherboard revision number     : B0
Model number                    : WS-C2960+24PC-L
System serial number            : FCW1816B1WV
Top Assembly Part Number        : 800-40259-01
Top Assembly Revision Number    : C0
Version ID                      : V01
CLEI Code Number                : CMMKU00ARA
Hardware Board Revision Number  : 0x03

Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
*    1 26    WS-C2960+24PC-L    15.0(2)SE6            C2960-LANBASEK9-M

Configuration register is 0xF

Switch#sh inv
NAME: "1", DESCR: "WS-C2960+24PC-L"
PID: WS-C2960+24PC-L   , VID: V01  , SN: FCW1816B1WV

Frequent Contributor

did you verifyed image file?

did you verifyed image file? before reload it?


verif     flash:c2960-lanbasek9-mz.122-55.SE9.bin


it will calculate checksumm

and dont forget to rate post


Ok, a few things with this.

Ok, a few things with this. 

Switch#dir flash:
Directory of flash:/

    2  -rwx        1919   Mar 1 1993 00:01:08 +00:00  private-config.text
    3  -rwx    11792256   Jan 1 1970 00:58:51 +00:00  c2960-lanbasek9-mz.150-2.SE6.bin
    4  -rwx        3096   Mar 1 1993 00:01:08 +00:00  multiple-fs
    6  -rwx     9821824   Jan 1 1970 00:01:58 +00:00  c2960-lanbasek9-mz.122-55.SE9.bin
    7  -rwx        1561   Mar 1 1993 00:01:08 +00:00  config.text


Switch#verify flash:c2960-lanbasek9-mz.122-55.SE9.bin


Switch#verify flash:/c2960-lanbasek9-mz.122-55.SE9.bin


Switch#verify flash:c2960-lanbasek9-mz.122-55.SE9.bin
File system hash verification failed for file flash:c2960-lanbasek9-mz.122-55.SE9.bin(No such file or directory).


Switch#verify /md5 flash:c2960-lanbasek9-mz.122-55.SE9.bin



verify /md5 (flash:c2960-lanbasek9-mz.122-55.SE9.bin) = a426418bb0957afd3184612592b253df


fciv shows the original file value to be different:

C:\Program Files (x86)\teraterm>fciv c2960-lanbasek9-mz.122-55.SE9
// File Checksum Integrity Verifier version 2.05.
e668bede8824f56c576f007e1ed85f31 c2960-lanbasek9-mz.122-55.se9.bin



The md5 checksum changed for another image after it was uploaded to the switch: c2960-lanbasek9-mz.150-2.SE6.bin

However, there are no issues booting from this image.


Switch#verify /md5 c2960-lanbasek9-mz.150-2.SE6.bin


verify /md5 (flash:c2960-lanbasek9-mz.150-2.SE6.bin) = 3771cdaaccee60e5d8163ca593d825d1


C:\Program Files (x86)\teraterm>fciv c2960-lanbasek9-mz.150-2.SE6.bin -md5
// File Checksum Integrity Verifier version 2.05.
7590376c9a1c17fcbd019b48d8f4c2c9 c2960-lanbasek9-mz.150-2.se6.bin


Thanks for your replies!





Frequent Contributor

file in your flash is not

both ios files in your flash are not good. corrupted. copy again and verify.


Switch#verify /md5 flash:c2960-lanbasek9-mz.122-55.SE9.bin



verify /md5 (flash:c2960-lanbasek9-mz.122-55.SE9.bin) = a426418bb0957afd3184612592b253df
Description: LAN BASE
Release: 12.2.55-SE9
Release Date: 18/Mar/2014
File Name: c2960-lanbasek9-mz.122-55.SE9.bin
Min Memory: DRAM 64 MB Flash 32 MB
Size: 9.37 MB (9821732 bytes)
MD5 Checksum: e668bede8824f56c576f007e1ed85f31
Release Notes for 12.2(55)SE9 | Field Notices
and dont forget to rate posts

I am getting similar results

I am getting similar results with a WS-C2960-48PST-L. The switch was previously was running 15.0 and I wanted to downgrade to 12.2. I loaded the new 12.2 software and got the looping "Unexpected exception to CPUvector 1100". I have run "format flash:" and the boot process hangs after this message, "...uncompressed and installed, entry point: 0x3000 executing…". It was hung for at least 10 minutes, I didn't try letting it go longer.

I also tried "archive download-sw /force-ucode-reload" when attempting to downgrade to 12.2 and I am sure that my images were not corrupt. IE. the "verify /md5" command checked out OK.

I am now installing 15.0 via XMODEM, a slow process...

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