If a chain went through a genesis restart without an IBC upgrade proposal updating the client can result in an error due to blocks at lower heights not being available.
For example if we have two chains
ibc-1, a client
07-tendermint-0 hosted on chain
ibc-0 and an Archive Node with its RPC address
ibc-0 goes through a genesis restart without an IBC upgrade proposal, trying to update client
07-tendermint-0 will result in an error:
ERROR failed during a client operation: error raised while updating client: failed
building header with error: Light client error for RPC address network1-1:
Internal error: height 26 is not available, lowest height is 1101 (code: -32603):
In this case, to update the client at a height higher than
1101 for example
1102, the following command can be used.
hermes update client --height 1102 --archive-address http://127.0.0.1:28000 --restart-height 1101 --host-chain ibc-1 --client 07-tendermint-0
Once this command is successful, updating the client should then work as usual.