diff --git a/nova/exception.py b/nova/exception.py
index 0be8f0f959..8c187eee65 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -2251,10 +2251,7 @@ class InvalidInventory(Invalid):
 # An exception with this name is used on both sides of the placement/
 # nova interaction.
 class InventoryInUse(InvalidInventory):
-    # NOTE(mriedem): This message cannot change without impacting the
-    # nova.scheduler.client.report._RE_INV_IN_USE regex.
-    msg_fmt = _("Inventory for '%(resource_classes)s' on "
-                "resource provider '%(resource_provider)s' in use.")
+    pass
 
 
 class UnsupportedPointerModelRequested(Invalid):
diff --git a/nova/scheduler/client/report.py b/nova/scheduler/client/report.py
index 07532dd35d..9c013eddc1 100644
--- a/nova/scheduler/client/report.py
+++ b/nova/scheduler/client/report.py
@@ -18,7 +18,6 @@ import contextlib
 import copy
 import functools
 import random
-import re
 import time
 
 from keystoneauth1 import exceptions as ks_exc
@@ -41,8 +40,6 @@ from nova import utils
 
 CONF = nova.conf.CONF
 LOG = logging.getLogger(__name__)
-_RE_INV_IN_USE = re.compile("Inventory for (.+) on resource provider "
-                            "(.+) in use")
 WARN_EVERY = 10
 RESHAPER_VERSION = '1.30'
 CONSUMER_GENERATION_VERSION = '1.28'
@@ -173,19 +170,6 @@ def _move_operation_alloc_request(source_allocs, dest_alloc_req):
     return new_alloc_req
 
 
-def _extract_inventory_in_use(body):
-    """Given an HTTP response body, extract the resource classes that were
-    still in use when we tried to delete inventory.
-
-    :returns: String of resource classes or None if there was no InventoryInUse
-              error in the response body.
-    """
-    match = _RE_INV_IN_USE.search(body)
-    if match:
-        return match.group(1)
-    return None
-
-
 def get_placement_request_id(response):
     if response is not None:
         return response.headers.get(request_id.HTTP_RESP_HEADER_REQUEST_ID)
@@ -946,12 +930,12 @@ class SchedulerReportClient(object):
         if resp.status_code == 409:
             # If a conflict attempting to remove inventory in a resource class
             # with active allocations, raise InventoryInUse
-            rc = _extract_inventory_in_use(resp.text)
-            if rc is not None:
-                raise exception.InventoryInUse(
-                    resource_classes=rc,
-                    resource_provider=rp_uuid,
-                )
+            err = resp.json()['errors'][0]
+            # TODO(efried): If there's ever a lib exporting symbols for error
+            # codes, use it.
+            if err['code'] == 'placement.inventory.inuse':
+                # The error detail includes the resource class and provider.
+                raise exception.InventoryInUse(err['detail'])
             # Other conflicts are generation mismatch: raise conflict exception
             raise exception.ResourceProviderUpdateConflict(
                 uuid=rp_uuid, generation=generation, error=resp.text)
diff --git a/nova/tests/functional/test_report_client.py b/nova/tests/functional/test_report_client.py
index a965aacac9..b6bf1747cb 100644
--- a/nova/tests/functional/test_report_client.py
+++ b/nova/tests/functional/test_report_client.py
@@ -702,10 +702,11 @@ class SchedulerReportClientTests(SchedulerReportClientTestBase):
             }
             # Allocation bumped the generation, so refresh to get the latest
             self.client._refresh_and_get_inventory(self.context, uuids.cn)
-            self.assertRaises(
-                exception.InventoryInUse,
-                self.client.set_inventory_for_provider,
-                self.context, uuids.cn, bad_inv)
+            msgre = (".*update conflict: Inventory for 'SRIOV_NET_VF' on "
+                     "resource provider '%s' in use..*" % uuids.cn)
+            with self.assertRaisesRegex(exception.InventoryInUse, msgre):
+                self.client.set_inventory_for_provider(self.context, uuids.cn,
+                                                       bad_inv)
             self.assertEqual(
                 inv,
                 self.client._get_inventory(
@@ -713,10 +714,9 @@ class SchedulerReportClientTests(SchedulerReportClientTestBase):
 
             # Same result if we try to clear all the inventory
             bad_inv = {}
-            self.assertRaises(
-                exception.InventoryInUse,
-                self.client.set_inventory_for_provider,
-                self.context, uuids.cn, bad_inv)
+            with self.assertRaisesRegex(exception.InventoryInUse, msgre):
+                self.client.set_inventory_for_provider(self.context, uuids.cn,
+                                                       bad_inv)
             self.assertEqual(
                 inv,
                 self.client._get_inventory(