Today I was confronted with the following problem : I was adding 2 switches to an already existing 3750 stack setup.

The way to do that is to connect the new switches to the stack with stack cables and then power them up, the stack sees the new switches and tries to add them to the stack.

The only problem is my 2 new switches had a newer version of IOS on them and so the stack would refuse to add them. It would try to automatically upgrade the IOS version on the new switches but would fail.

So I then tried to update manually (as explained here) I used the following command :

archive download-sw /allow-feature-upgrade /destination-system 3 /force-reload /imageonly /overwrite flash1:/c3750-advipservicesk9-mz.122-46.SE.bin

But then the system would complain that the image wasn't a valid IOS image. I ended figuring out that the command was expecting a tar archive and not a bin but it was the only thing I had.

The solution to this problem is to manually upgrade each switch. Here is how you do this, I used this as the basis for this.

  • The first thing I needed to do is to make room for the image on the destination switch (here it's switch 3 of the stack)
delete flash3:/c3750-ipservicesk9-mz.122-55.SE1.bin
  • Then we copy the image to the destination switch
copy flash1:/c3750-advipservicesk9-mz.122-46.SE.bin flash3:
  • Now we tell switch 3 to boot on this image
conf t
boot system switch 3 flash:/c3750-advipservicesk9-mz.122-46.SE.bin
  • Now we need to reboot that particular switch (and not the whole stack as suggested in the previous link)
reload slot 3

  • When the switch reboots it will be able to join the stack without a problem

  • Now we just need to repeat the operation for switch 4