diff --git a/hgext3rd/phabstatus.py b/hgext3rd/phabstatus.py
index 9b898ea82b..95204806c4 100644
--- a/hgext3rd/phabstatus.py
+++ b/hgext3rd/phabstatus.py
@@ -80,12 +80,12 @@ def getdiffstatus(repo, *diffid):
     except conduit.ClientError as ex:
         msg = _('Error talking to phabricator. No diff information can be '
                 'provided.\n')
-        hint = _("Error info: ") + str(ex)
+        hint = _("Error info: %s\n") % str(ex)
         return _fail(repo, diffid, msg, hint)
     except arcconfig.ArcConfigError as ex:
         msg = _('arcconfig configuration problem. No diff information can be '
                 'provided.\n')
-        hint = _("Error info: ") + str(ex)
+        hint = _("Error info: %s\n") % str(ex)
         return _fail(repo, diffid, msg, hint)
 
     if not resp:
diff --git a/phabricator/conduit.py b/phabricator/conduit.py
index c58e902197..3df54a8d0f 100644
--- a/phabricator/conduit.py
+++ b/phabricator/conduit.py
@@ -34,9 +34,13 @@ class Client(object):
 
     def apply_arcconfig(self, config):
         self._host = config.get('conduit_uri', DEFAULT_HOST)
-        hostconfig = config['hosts'][self._host]
-        self._user = hostconfig['user']
-        self._cert = hostconfig['cert']
+        try:
+            hostconfig = config['hosts'][self._host]
+            self._user = hostconfig['user']
+            self._cert = hostconfig['cert']
+        except KeyError:
+            raise arcconfig.ArcConfigError('arcrc is missing user credentials '
+                                           'for host %s' % self._host)
         self._actas = self._user
         self._connection = None
 
diff --git a/tests/test-phabstatus.t b/tests/test-phabstatus.t
index d936d80445..6887f0ae1a 100644
--- a/tests/test-phabstatus.t
+++ b/tests/test-phabstatus.t
@@ -17,7 +17,8 @@ With an invalid arc configuration
 
   $ hg log -T '{phabstatus}\n' -r .
   arcconfig configuration problem. No diff information can be provided.
-  Error info: no .arcconfig foundError
+  Error info: no .arcconfig found
+  Error
 
 Configure arc...
 
@@ -37,7 +38,8 @@ And now with bad responses:
   > EOF
   $ HG_ARC_CONDUIT_MOCK=$TESTTMP/mockduit hg log -T '{phabstatus}\n' -r .
   Error talking to phabricator. No diff information can be provided.
-  Error info: failed, yoError
+  Error info: failed, yo
+  Error
 
 Missing status field is treated as an error
 
@@ -62,3 +64,12 @@ Make sure the template keywords are documented correctly
   $ hg help templates | egrep 'phabstatus|syncstatus'
       phabstatus    String. Return the diff approval status for a given hg rev
       syncstatus    String. Return whether the local revision is in sync with
+
+Make sure we get decent error messages when .arcrc is missing credential
+information.  We intentionally do not use HG_ARC_CONDUIT_MOCK for this test,
+so it tries to parse the (empty) arc config files.
+
+  $ hg log -T '{phabstatus}\n' -r .
+  arcconfig configuration problem. No diff information can be provided.
+  Error info: arcrc is missing user credentials for host https://phabricator.fb.com/api/
+  Error