diff --git a/kallithea/controllers/compare.py b/kallithea/controllers/compare.py
--- a/kallithea/controllers/compare.py
+++ b/kallithea/controllers/compare.py
@@ -210,7 +210,8 @@ class CompareController(BaseRepoControll
             h.flash(msg, category='error')
             return redirect(url('compare_home', repo_name=c.repo_name))
 
-        c.a_rev = self._get_ref_rev(org_repo, org_ref_type, org_ref_name)
+        c.a_rev = self._get_ref_rev(org_repo, org_ref_type, org_ref_name,
+            returnempty=True)
         c.cs_rev = self._get_ref_rev(other_repo, other_ref_type, other_ref_name)
 
         c.compare_home = False
diff --git a/kallithea/controllers/pullrequests.py b/kallithea/controllers/pullrequests.py
--- a/kallithea/controllers/pullrequests.py
+++ b/kallithea/controllers/pullrequests.py
@@ -580,7 +580,10 @@ class PullrequestsController(BaseRepoCon
                 c.cs_branch_name = org_scm_instance.get_changeset(c.cs_ref_name).branch # use ref_type ?
             other_branch_name = c.a_ref_name
             if c.a_ref_type != 'branch':
-                other_branch_name = other_scm_instance.get_changeset(c.a_ref_name).branch # use ref_type ?
+                try:
+                    other_branch_name = other_scm_instance.get_changeset(c.a_ref_name).branch # use ref_type ?
+                except EmptyRepositoryError:
+                    other_branch_name = 'null' # not a branch name ... but close enough
             # candidates: descendants of old head that are on the right branch
             #             and not are the old head itself ...
             #             and nothing at all if old head is a descendent of target ref name
diff --git a/kallithea/lib/base.py b/kallithea/lib/base.py
--- a/kallithea/lib/base.py
+++ b/kallithea/lib/base.py
@@ -436,7 +436,7 @@ class BaseRepoController(BaseController)
                                     c.repo_name, self.authuser.user_id)
 
     @staticmethod
-    def _get_ref_rev(repo, ref_type, ref_name):
+    def _get_ref_rev(repo, ref_type, ref_name, returnempty=False):
         """
         Safe way to get changeset. If error occurs show error.
         """
@@ -444,6 +444,8 @@ class BaseRepoController(BaseController)
         try:
             return repo.scm_instance.get_ref_revision(ref_type, ref_name)
         except EmptyRepositoryError as e:
+            if returnempty:
+                return repo.scm_instance.EMPTY_CHANGESET
             h.flash(h.literal(_('There are no changesets yet')),
                     category='error')
             raise webob.exc.HTTPNotFound()