diff --git a/nova/pci/request.py b/nova/pci/request.py
index fe12bb50fd..6ef87df551 100644
--- a/nova/pci/request.py
+++ b/nova/pci/request.py
@@ -121,6 +121,23 @@ _ALIAS_SCHEMA = {
 }
 
 
+def _validate_aliases(aliases):
+    """Checks the parsed aliases for common mistakes and raise easy to parse
+    error messages
+    """
+    if CONF.filter_scheduler.pci_in_placement:
+        alias_with_multiple_specs = [
+            name for name, spec in aliases.items() if len(spec[1]) > 1]
+        if alias_with_multiple_specs:
+            raise exception.PciInvalidAlias(
+                "The PCI alias(es) %s have multiple specs but "
+                "[filter_scheduler]pci_in_placement is True. The PCI in "
+                "Placement feature only supports one spec per alias. You can "
+                "assign the same resource_class to multiple [pci]device_spec "
+                "matchers to allow using different devices for the same alias."
+                % ",".join(alias_with_multiple_specs))
+
+
 def _get_alias_from_config() -> Alias:
     """Parse and validate PCI aliases from the nova config.
 
@@ -177,6 +194,7 @@ def _get_alias_from_config() -> Alias:
     except Exception as exc:
         raise exception.PciInvalidAlias(reason=str(exc))
 
+    _validate_aliases(aliases)
     return aliases
 
 
diff --git a/nova/tests/functional/regressions/test_bug_2102038.py b/nova/tests/functional/regressions/test_bug_2102038.py
index e867e27c6f..f1f1d13770 100644
--- a/nova/tests/functional/regressions/test_bug_2102038.py
+++ b/nova/tests/functional/regressions/test_bug_2102038.py
@@ -49,7 +49,11 @@ class MultipleSpecPerAliasWithPCIInPlacementTest(
             flavor_id=flavor_id,
             networks=[],
         )
-        # This is bug 2102038 as nova does not handle the internal ValueError
-        # and therefore returns HTTP 500 instead of returning 400 Bad Request
-        # with a message pointing to the unsupported alias config.
-        self.assertEqual(500, exc.response.status_code)
+        self.assertEqual(400, exc.response.status_code)
+        self.assertIn(
+            "The PCI alias(es) a-vf have multiple specs but "
+            "[filter_scheduler]pci_in_placement is True. The PCI in Placement "
+            "feature only supports one spec per alias. You can assign the "
+            "same resource_class to multiple [pci]device_spec matchers to "
+            "allow using different devices for the same alias.",
+            exc.response.text)
diff --git a/nova/tests/unit/pci/test_request.py b/nova/tests/unit/pci/test_request.py
index be9c6be877..fcd14d117c 100644
--- a/nova/tests/unit/pci/test_request.py
+++ b/nova/tests/unit/pci/test_request.py
@@ -120,6 +120,28 @@ class PciRequestTestCase(test.NoDBTestCase):
             }])
         self.assertEqual(expected_result, result['QuickAssist'])
 
+    def test_get_alias_from_config_multispec_rejected_pci_in_placement(self):
+        _fake_alias = jsonutils.dumps({
+            "name": "QuickAssist",
+            "capability_type": "pci",
+            "product_id": "4444",
+            "vendor_id": "8086",
+            "device_type": "type-PCI",
+        })
+
+        self.flags(pci_in_placement=True, group='filter_scheduler')
+        self.flags(alias=[_fake_alias1, _fake_alias], group='pci')
+
+        ex = self.assertRaises(
+            exception.PciInvalidAlias, request._get_alias_from_config)
+        self.assertEqual(
+            "The PCI alias(es) QuickAssist have multiple specs but "
+            "[filter_scheduler]pci_in_placement is True. The PCI in Placement "
+            "feature only supports one spec per alias. You can assign the "
+            "same resource_class to multiple [pci]device_spec matchers to "
+            "allow using different devices for the same alias.",
+            str(ex))
+
     def _test_get_alias_from_config_invalid(self, alias):
         self.flags(alias=[alias], group='pci')
         self.assertRaises(