Copying ios to flash via serial

Unanswered Question
Aug 13th, 2007

I have just downloaded a new image to flash via a serial cable on a Cisco 837. The Download completed and then erazed the flash, but the checksum failed. Here is the output:

Expected checksum: 3d7a, calculated checksum:814

open: file "c837-k9o3y6-mz.124-5a.bin" not found

open(): open Error = -1

loadprog: error - on file open

Any ideas what to do next?

I have this problem too.
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purohit_810 Mon, 08/13/2007 - 04:16

Your router is not able to boot by your new IOS.

Please squeeze the flsh, see flash space and upload new IOS.

If it will not work that delete IOS, Upload new IOS by XMODEM utility in hyperterminal.


Dharmesh Purohit

whiteford Mon, 08/13/2007 - 04:18

I can only get into rommon and can't see squeeze as an option.

Richard Burts Mon, 08/13/2007 - 04:29


I am not sure if that router supports tftpdnld in rommon. If it does it would be easier to use tftpdnld than xmodem. If tftpdnld does not work then I believe that the only option for you is xmodem to transfer the image over the console connection. I believe that xmodem will take care of erasing flash so I would not worry too much about trying to squeeze flash from rommon.

I am not sure about the original post. When you say you loaded over a serial cable are you saying that you were connected to the console and loaded the IOS over the console connection? Is so was that using xmodem? If you have made one attempt to use xmodem that produced a bad checksum, I might suggest getting a new copy of the IOS image to your PC since it is not clear whether the xmodem copy process had an error or whether the image you are copying might have a problem.



whiteford Mon, 08/13/2007 - 04:41

Sorry I shoudl of mentioned I am using Xmodem, I will attempt one more time. Problem is this is the only image and I don't have access to download from the Cisco website.

whiteford Mon, 08/13/2007 - 05:18

It just failed again, it boots up saying:

Boot: cannot determine first file name on device "flash"

rommon 1 >

Richard Burts Mon, 08/13/2007 - 05:22


Are there any messages indicating that there might be problems with the xmodem copy process? Can you post the messages generated as you initiate the xmodem copy to the point where it attempts to reboot?

Does that router support tftpdnld from rommon?



whiteford Mon, 08/13/2007 - 06:47

This is all i can get from HT:

rommon 1 > xmodem -c c837-k9o3y6-mz.124-5a.bin

Do not start the sending program yet...

File size Checksum File name

8393080 bytes (0x801178) 0x3d7a c837-k9o3y6-mz.124-5a.bin (bad checksum:


WARNING: All existing data in bootflash will be lost!

Invoke this application only for disaster recovery.

Do you wish to continue? y/n [n]: y

Ready to receive file c837-k9o3y6-mz.124-5a.bin

Download Complete!

Copying file c837-k9o3y6-mz.124-5a.bin to flash.

Erasing flash ..................................................................


Programming flash .Programming flash .Programming flash ........................

.........................................Checksum failed on c837-k9o3y6-mz.124-5


Expected checksum: 3d7a, calculated checksum: 814

open: file "c837-k9o3y6-mz.124-5a.bin" not found

open(): Open Error = -1

loadprog: error - on file open

rommon 2 >

DELL ACORD Mon, 08/13/2007 - 07:01

Can you post the results of command rommon>dir flash:



whiteford Mon, 08/13/2007 - 07:17

here it is:

rommon 3 > dir flash:

File size Checksum File name

8393080 bytes (0x801178) 0x3d7a c837-k9o3y6-mz.124-5a.bin (bad checksum:


rommon 4 >

DELL ACORD Mon, 08/13/2007 - 07:24

Thanks for the post.

Do you have access to another 837 or have a back up copy some where of the .bin file?

Probably already thought of this, but just wanted to be sure.



whiteford Mon, 08/13/2007 - 07:28

Not on site, but i can get one, can I copy the image from one cisco router to my PC and then use Xmodem to this faulty router?

If so how?


Richard Burts Mon, 08/13/2007 - 07:44


If you can get another copy that would be very good. Do you have software on your PC that runs TFTP server? To copy the IOS image from the router you will need your PC to act as a TFTP server. If you do not have TFTP server software there are several free versions that you could use.

Once you have the TFTP software you would start the TFTP software to make your PC a TFTP server. Then on the router that has the image that you want to copy you wold login, go to privilege mode and enter the command copy flash: tftp:

you then follow the prompts to identify the server (your PC) and the image name. then the router will copy the image from its flash to your PC. Once you have the new copy of the image you can use it for xmodem.



Richard Burts Mon, 08/13/2007 - 07:04


Thanks for posting the messages generated during the xmodem copy. I do not see any signs of an error during the copy process and only the invalid checksum. You might try the copy with a different console cable or try it with a different console speed set. But I am not optimistic that either of these will really solve the problem. My guess is that the image that you are attempting to copy has somehow become corrupted.



whiteford Mon, 08/13/2007 - 07:20

Problem is I downloaded this a while ago and no longer have access to download from Cisco, anywhere else I can get one? This one is only about 8mb, I have a later version which is now too much for the age of my current 837.


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