I've changed my base URI via the command line and confirmed the change:

phab_admin@phabricator:~/phabricator-install/phabricator# ./bin/config get phabricator.base-uri
{

"config" : [
  {
    "key"    : "phabricator.base-uri",
    "source" : "local",
    "value"  : "http:\/\/phabricator.domainB.local"
  }
]

}

However when I browse to the new base URI I get the following error "[Core Exception/Exception] Specified domain phabricator.domainB.local is not configured for Phabricator requests. Please use http://phabricator.domainA.local/ to visit this instance."

Any suggestions as to what the issue might be please?
Thanks