Cisco router missing startup-configuration after reload [FIX]


I recently got my hands on a few Cisco 1760 routers to make up part of a frame relay CCNP lab, unfortunately when reloading the devices either using the command or by power the configuration was missing and I was presented with the following display:

--- System Configuration Dialog ---
Would you like to enter the initial configuration dialog? [yes/no]: no

So first thing to check is, am I using the correct command? I typed in the following and reloaded, sure enough the initial configuration dialog popped up again with no configuration loaded on the device.

write mem
copy running-configuration statup-configuration

Good new’s is that I wasn’t been stupid and no matter what command I tried the configuration after reload was simply blank, like you would expect when your first power on the router. The bad side was I was still no closer to getting my configuration actually saved on the device.

After doing a bit of searching I found some information on the “configuration register”, basically a pointer in the IOS that defines where the configuration will be loaded from. In my case this was set to “0x2142” which bypasses the startup-configuration, as you can see below by running the “show version” command

Router#show version
...[output omitted]...
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read ONLY)
Configuration register is 0x2142

The solution is to correct the configuration register and set to “0x2102”, which can be done using the below commands. I would suggesting setting something like the hostname so it’s easy to see if this works, also you will need to reload for the command to take effect.

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#config-register 0x2102

Before you reload you can confirm the changes by running the “sh ver” command again, you should see something like this on the last line of output:

Configuration register is 0x2142 (will be 0x2102 at next reload)

Technology enthusiastic with many ongoing online projects one of which is this personal blog PingBin. While also working full time within a data center designing and maintaining the network infrastructure.

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