Configuration changes in postgres

In a Master-slave PostgreSQL setup in which slave server is on hot-standby.

But whenever i change any configuration parameter in master like max_connection and restart the postgres service, the slave is unable to execute any query and abnormally shutdown until i do same changes in slave config.

Whats the exact issue?
can't we keep different config's on master and slave?
And if we need to change the parameter, is it necessary to restart both master and slave node server ?

Thanks