diff --git a/ironic/api/controllers/v1/utils.py b/ironic/api/controllers/v1/utils.py
index 04525ff651..8de2d156df 100644
--- a/ironic/api/controllers/v1/utils.py
+++ b/ironic/api/controllers/v1/utils.py
@@ -86,11 +86,13 @@ STANDARD_TRAITS = os_traits.get_traits()
 CUSTOM_TRAIT_PATTERN = "^%s[A-Z0-9_]+$" % os_traits.CUSTOM_NAMESPACE
 CUSTOM_TRAIT_REGEX = re.compile(CUSTOM_TRAIT_PATTERN)
 
-TRAITS_SCHEMA = {'anyOf': [
-    {'type': 'string', 'minLength': 1, 'maxLength': 255,
-     'pattern': CUSTOM_TRAIT_PATTERN},
-    {'type': 'string', 'enum': STANDARD_TRAITS},
-]}
+TRAITS_SCHEMA = {
+    'type': 'string', 'minLength': 1, 'maxLength': 255,
+    'anyOf': [
+        {'pattern': CUSTOM_TRAIT_PATTERN},
+        {'enum': STANDARD_TRAITS},
+    ]
+}
 
 LOCAL_LINK_BASE_SCHEMA = {
     'type': 'object',
diff --git a/ironic/common/args.py b/ironic/common/args.py
index 94cfe8841b..bd13e3eafd 100755
--- a/ironic/common/args.py
+++ b/ironic/common/args.py
@@ -211,12 +211,17 @@ def _validate_schema(name, value, schema):
     try:
         jsonschema.validate(value, schema)
     except jsonschema.exceptions.ValidationError as e:
-
-        # The error message includes the whole schema which can be very
-        # large and unhelpful, so truncate it to be brief and useful
-        error_msg = ' '.join(str(e).split("\n")[:3])[:-1]
-        raise exception.InvalidParameterValue(
-            _('Schema error for %s: %s') % (name, error_msg))
+        error_msg = _('Schema error for %s: %s') % (name, e.message)
+        # Sometimes the root message is too generic, try to find a possible
+        # root cause:
+        cause = None
+        current = e
+        while current.context:
+            current = jsonschema.exceptions.best_match(current.context)
+            cause = current.message
+        if cause is not None:
+            error_msg += _('. Possible root cause: %s') % cause
+        raise exception.InvalidParameterValue(error_msg)
     return value
 
 
diff --git a/releasenotes/notes/jsonschema-4.8-1146d103b877cffd.yaml b/releasenotes/notes/jsonschema-4.8-1146d103b877cffd.yaml
new file mode 100644
index 0000000000..75c0a6c507
--- /dev/null
+++ b/releasenotes/notes/jsonschema-4.8-1146d103b877cffd.yaml
@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixes API error messages with jsonschema>=4.8. A possible root cause is
+    now detected for generic schema errors.