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SG300 Firmware Upgrade - Copy: Illegal software format

Following the process documented in the SG300 manual - When I select the firmware source file - Select File sx300_fw-14088.ros (I just downloaded from the Cisco website)  -  I receive the following error - Copy: Illegal software format.  What is the file extension of the firmware upgrade file?  What am I doing wrong?


Hi gmontanez01,

What is the current version of your boot code? More than likely there could be a version in between that needs to be reached prior to updating to that specific boot code.



In my case I was facing the same issue as everyone.


My_switch#copy tftp:// image

Copy: Illegal software format


I was upgrading from directly to the 1.4

After I download from the Cisco web site the intermediate version I can got sucessfull


Thanks a lot.

use ese firmware el y ahora no funciona mi switch como puedo iniciar en la otra imagen que tiene el firmware anterio??

Thanks a lot...

Jesus Christ. After hours of frustration I found your post. I was about to RMA this piece of crap. Upgrading firmware should not be this frustrating in 2017.

Right there with you.  Completely ridiculous process.  Finally updated!

Wow I bought the switch with old firmware (need 100mb not GB) and I've spent many hours trying to solve this upgrade problem. Never in all the switches and firewalls I have programed have I had this much trouble.CLI, TFTP, HTTP it doesn't matter except for the boot code. You must have V1.3.7.18 installed before updating to V1.4.7.06.

Once I realized that you have to expand the ' 1 ' to get to download the V1.3 FW, then things started going right.

Many thanks to support community.

Thanks a bunch!  As I had the same trouble as well.

Thank you.  I was having the same issue and had to step upgrade several times.  Another reason I prefer enterprise switches over SMB ones.  Unfortunately I still have some out there.

Hi Raul,

I understand that current upgrade it is a bit complicated but it is not always going to be the same challenge. Such a caution is usually communicated in release notes.

The reason for this is to accommodate bigger firmware with more additional features :-) 



Hi All,

Same Problem here, I have an old 1.3.x on my SG300-28.My Problem is now, that I cant find the Firmware, it Looks like Cisco has removed it from the download.

Without the iterim release, I can't upgrade anymore...

Anyone know where I can download the or can send it to me?

Hello. Check out my posts and screen grabs at the bottom of this page. is tricky to find but it's there.

All the best


Thanks for the info above.   I  was able to install the V1.3.7.18 ros file via http/https but cannot upload the boot loader via that option.


Our boot version is 1.1 and want to update it to 1.3.506 before 1.4x.  I tried TFTP and entered the ip of the server and file name of the rfb in UNC format.   I got the message download in progress, processing data banner, but copy failed TFTP server unreachable.


What is the easiest way to get the boot loader updated?  The files are on the file server or could be located anywhere that's easiest



Hi Jeff,

I'd recommend you always use the CLI to TFTP.. Seems to be easier on the SMB boxes. For example if your TFTP server was

copy tftp:// boot

Make sure your TFTP Server service is running on your server too, and that you don't have any Windows firewalls blocking TFTP. do a great free TFTP server if you need one.



Hi Matt,

Thanks.  I'll have a look at that as we don't have a tftp server setup yet.