diff --git a/boottest.py b/boottest.py
index 0effc50..74e3552 100644
--- a/boottest.py
+++ b/boottest.py
@@ -215,7 +215,18 @@ class BootTest(object):
 
     def get_status(self, name, version):
         """Return test status for the given source name and version."""
-        return self.pkglist[name][version]
+        try:
+            return self.pkglist[name][version]
+        except KeyError:
+            # This error handling accounts for outdated apt caches, when
+            # `boottest-britney` erroneously reports results for the
+            # current source version, instead of the proposed.
+            # Returning None here will block source promotion with:
+            # 'UNKNOWN STATUS' excuse. If the jobs are retried and its
+            # results find an up-to-date cache, the problem is gone.
+            print("E: [%s] - Missing boottest results for %s_%s" % (
+                time.asctime(), name, version))
+            return None
 
     def request(self, packages):
         """Requests boottests for the given sources list ([(src, ver),])."""
diff --git a/britney.conf b/britney.conf
index 827bd1f..8d9b285 100644
--- a/britney.conf
+++ b/britney.conf
@@ -66,7 +66,7 @@ ADT_ENABLE        = yes
 ADT_DEBUG         = no
 ADT_ARCHES        = amd64 i386
 
-BOOTTEST_ARCHES   = armhf
 BOOTTEST_ENABLE   = yes
 BOOTTEST_DEBUG    = yes
+BOOTTEST_ARCHES   = armhf amd64
 BOOTTEST_FETCH    = yes
diff --git a/tests/test_boottest.py b/tests/test_boottest.py
index b8ce9ed..6b0d088 100644
--- a/tests/test_boottest.py
+++ b/tests/test_boottest.py
@@ -301,6 +301,22 @@ args.func()
                  boottest.BootTest.EXCUSE_LABELS['FAIL']),
              '<li>Not considered'])
 
+    def test_unknonw(self):
+        # `Britney` does not block on missing boottest results for a
+        # particular source/version, in this case pyqt5-src_1.2 (not
+        # listed in the testing result history). Instead it renders
+        # excuses with 'UNKNOWN STATUS' and links to the corresponding
+        # jenkins jobs for further investigation. Source promotion is
+        # blocked, though.
+        context = [
+            ('pyqt5', {'Source': 'pyqt5-src', 'Version': '1.2',
+                       'Architecture': 'armhf'})]
+        self.do_test(
+            context,
+            [r'\bpyqt5-src\b.*\(- to .*>1.2<',
+             r'<li>Boottest result: UNKNOWN STATUS \(Jenkins: .*\)',
+             '<li>Not considered'])
+
     def create_hint(self, username, content):
         """Populates a hint file for the given 'username' with 'content'."""
         hints_path = os.path.join(