"lightningd: Config file /root/.lightning/config line 11: network=mainnet: Unknown network name 'mainnet'"

[p01nt3rgit]

version: elementsproject/lightningd:v25.12.1

setting network=mainnet causes lightningd failing to start with error

Unknown network name 'mainnet'

setting network=bitcoin works well

also after a successful lightningd start with network=bitcoins, setting back network=mainnet and restart it face again the same issue

in my understanding 'mainnet' should be a 'bitcoin' alias

[cdecker]

I am tempted to say this is a Won't Fix. As you correctly point out --network=bitcoin is the intended name for the network. We only provide a shorthand that matches bitcoind in the form of --mainnet which aliases to --network=bitcoin (and I already didn't like that, since aliasing is always bad), but otherwise bitcoin is being used consistently in CLN.