diff --git a/src/fastapi_aad_auth/_base/backend.py b/src/fastapi_aad_auth/_base/backend.py
index 1268037..9669e31 100644
--- a/src/fastapi_aad_auth/_base/backend.py
+++ b/src/fastapi_aad_auth/_base/backend.py
@@ -48,7 +48,7 @@ def check(self, request: Request, allow_session=True) -> Optional[Authentication
                 continue
             state = validator.check(request)
             self.logger.debug(f'Authentication state {state} from validator {validator}')
-            if state is not None:
+            if state is not None and state.is_authenticated():
                 break
         self.logger.info(f'Identified state {state}')
         return state
diff --git a/src/fastapi_aad_auth/_base/validators/token.py b/src/fastapi_aad_auth/_base/validators/token.py
index 5229a4e..a531e71 100644
--- a/src/fastapi_aad_auth/_base/validators/token.py
+++ b/src/fastapi_aad_auth/_base/validators/token.py
@@ -45,12 +45,16 @@ def __init__(
 
     def check(self, request: Request):
         """Check the authentication from the request."""
-        token = self.get_token(request)
-        if token is None:
-            return AuthenticationState.as_unauthenticated(None, None)
-        claims = self.validate_token(token)
-        user = self._get_user_from_claims(claims)
-        return AuthenticationState.authenticate_as(user, None, None)
+        state = AuthenticationState.as_unauthenticated(None, None)
+        try:
+            token = self.get_token(request)
+            if token is not None:
+                claims = self.validate_token(token)
+                user = self._get_user_from_claims(claims)
+                state = AuthenticationState.authenticate_as(user, None, None)
+        except Exception:
+            self.logger.exception('Error authenticating via token')
+        return state
 
     def get_token(self, request: Request):
         """Get the token from the request."""
diff --git a/src/fastapi_aad_auth/errors.py b/src/fastapi_aad_auth/errors.py
index b57558c..3139b7c 100644
--- a/src/fastapi_aad_auth/errors.py
+++ b/src/fastapi_aad_auth/errors.py
@@ -1,7 +1,7 @@
 """fastapi_aad_auth errors."""
 from starlette.responses import JSONResponse, Response
 
-
+from fastapi_aad_auth.utilities import is_interactive
 from fastapi_aad_auth.utilities.logging import getLogger
 
 logger = getLogger(__name__)
@@ -12,8 +12,7 @@ def base_error_handler(request, exception, error_type, error_message, templates,
     if context is None:
         context = {}
     logger.warning(f'Handling error {exception}')
-    status_code = 500
-    if any([u in request.headers['user-agent'] for u in ['Mozilla', 'Gecko', 'Trident', 'WebKit', 'Presto', 'Edge', 'Blink']]):
+    if is_interactive(request):
         logger.info('Interactive environment so returning error template')
         logger.debug(f'Path: {template_path}')
         error_context = context.copy()
diff --git a/src/fastapi_aad_auth/utilities/__init__.py b/src/fastapi_aad_auth/utilities/__init__.py
index 71830fb..bd262df 100644
--- a/src/fastapi_aad_auth/utilities/__init__.py
+++ b/src/fastapi_aad_auth/utilities/__init__.py
@@ -1,26 +1,33 @@
 """Utilities."""
 import importlib
 
+from starlette.requests import Request
+
 from fastapi_aad_auth.utilities import logging  # noqa: F401
 from fastapi_aad_auth.utilities import urls  # noqa: F401
 from fastapi_aad_auth.utilities.deprecate import DeprecatableFieldsMixin, deprecate, deprecate_module, DeprecatedField, is_deprecated  # noqa: F401
 
 
-def bool_from_env(env_value):
+def is_interactive(request: Request):
+    """Check if a request is from an interactive client."""
+    return any([u in request.headers['user-agent'] for u in ['Mozilla', 'Gecko', 'Trident', 'WebKit', 'Presto', 'Edge', 'Blink']])
+
+
+def bool_from_env(env_value: str):
     """Convert environment variable to boolean."""
     if isinstance(env_value, str):
         env_value = env_value.lower() in ['true', '1']
     return env_value
 
 
-def list_from_env(env_value):
+def list_from_env(env_value: str):
     """Convert environment variable to list."""
     if isinstance(env_value, str):
         env_value = [u for u in env_value.split(',') if u]
     return env_value
 
 
-def klass_from_str(value):
+def klass_from_str(value: str):
     """Convert an import path to a class."""
     if isinstance(value, str):
         if ':' in value:
@@ -34,7 +41,7 @@ def klass_from_str(value):
     return value
 
 
-def expand_doc(klass):
+def expand_doc(klass: type):
     """Expand pydantic model documentation to enable autodoc."""
     docs = ['', '', 'Keyword Args:']
     for name, field in klass.__fields__.items():