diff --git a/src/Grant/AbstractGrant.php b/src/Grant/AbstractGrant.php
index c559656c..bd0794b3 100644
--- a/src/Grant/AbstractGrant.php
+++ b/src/Grant/AbstractGrant.php
@@ -13,7 +13,7 @@ namespace League\OAuth2\Server\Grant;
 
 use League\OAuth2\Server\AuthorizationServer;
 use League\OAuth2\Server\Entity\Scope;
-use League\OAuth2\Server\Exception\ClientException;
+use League\OAuth2\Server\Exception;
 
 /**
  * Abstract grant class
@@ -121,7 +121,7 @@ abstract class AbstractGrant implements GrantTypeInterface
             $this->server->getDefaultScope() === null &&
             count($scopesList) === 0
         ) {
-            throw new ClientException(sprintf($this->server->getExceptionMessage('invalid_request'), 'scope'), 0);
+            throw new Exception\InvalidRequestException('scope');
         } elseif (count($scopesList) === 0 && $this->server->getDefaultScope() !== null) {
             if (is_array($this->server->getDefaultScope())) {
                 $scopesList = $this->server->getDefaultScope();
@@ -139,7 +139,7 @@ abstract class AbstractGrant implements GrantTypeInterface
             );
 
             if (($scope instanceof Scope) === false) {
-                throw new ClientException(sprintf($this->server->getExceptionMessage('invalid_scope'), $scopeItem), 4);
+                throw new Exception\InvalidScopeException($scopeItem);
             }
 
             $scopes[$scope->getId()] = $scope;
diff --git a/src/Grant/AuthCode.php b/src/Grant/AuthCode.php
index 5a2250d0..b374b07e 100644
--- a/src/Grant/AuthCode.php
+++ b/src/Grant/AuthCode.php
@@ -24,7 +24,6 @@ use League\OAuth2\Server\Util\SecureKey;
 use League\OAuth2\Server\Storage\SessionInterface;
 use League\OAuth2\Server\Storage\ClientInterface;
 use League\OAuth2\Server\Storage\ScopeInterface;
-use League\OAuth2\Server\Exception\ClientException;
 
 /**
  * Auth code grant class
@@ -82,42 +81,27 @@ class AuthCode extends AbstractGrant
         // Get required params
         $clientId = $this->server->getRequest()->request->get('client_id', null);
         if (is_null($clientId)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'client_id'),
-                0
-            );
+            throw new Exception\InvalidRequestException('client_id');
         }
 
         $redirectUri = $this->server->getRequest()->request->get('redirect_uri', null);
         if (is_null($redirectUri)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'redirect_uri'),
-                0
-            );
+            throw new Exception\InvalidRequestException('redirect_uri');
         }
 
         $state = $this->server->getRequest()->request->get('state', null);
         if ($this->server->stateParamRequired() === true && is_null($state)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'state'),
-                0
-            );
+            throw new Exception\InvalidRequestException('state');
         }
 
         $responseType = $this->server->getRequest()->request->get('response_type', null);
         if (is_null($responseType)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'response_type'),
-                0
-            );
+            throw new Exception\InvalidRequestException('response_type');
         }
 
         // Ensure response type is one that is recognised
         if ( ! in_array($responseType, $this->server->getResponseTypes())) {
-            throw new ClientException(
-                $this->server->getExceptionMessage('unsupported_response_type'),
-                3
-            );
+            throw new Exception\UnsupportedResponseTypeException();
         }
 
         // Validate client ID and redirect URI
@@ -129,7 +113,7 @@ class AuthCode extends AbstractGrant
         );
 
         if (($client instanceof Client) === false) {
-            throw new ClientException(AuthorizationServer::getExceptionMessage('invalid_client'), 8);
+            throw new Exception\InvalidClientException();
         }
 
         // Validate any scopes that are in the request
@@ -186,26 +170,17 @@ class AuthCode extends AbstractGrant
         // Get the required params
         $clientId = $this->server->getRequest()->request->get('client_id', null);
         if (is_null($clientId)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'client_id'),
-                0
-            );
+            throw new Exception\InvalidRequestException('client_id');
         }
 
         $clientSecret = $this->server->getRequest()->request->get('client_secret', null);
         if (is_null($clientSecret)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'client_secret'),
-                0
-            );
+            throw new Exception\InvalidRequestException('client_secret');
         }
 
         $redirectUri = $this->server->getRequest()->request->get('redirect_uri', null);
         if (is_null($redirectUri)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'redirect_uri'),
-                0
-            );
+            throw new Exception\InvalidRequestException('redirect_uri');
         }
 
         // Validate client ID and client secret
@@ -217,32 +192,23 @@ class AuthCode extends AbstractGrant
         );
 
         if (($client instanceof Client) === false) {
-            throw new ClientException(AuthorizationServer::getExceptionMessage('invalid_client'), 8);
+            throw new Exception\InvalidClientException();
         }
 
         // Validate the auth code
         $authCode = $this->server->getRequest()->request->get('code', null);
         if (is_null($authCode)) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'code'),
-                0
-            );
+            throw new Exception\InvalidRequestException('code');
         }
 
         $code = $this->server->getStorage('auth_code')->get($authCode);
         if (($code instanceof AC) === false) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'code'),
-                9
-            );
+            throw new Exception\InvalidRequestException('code');
         }
 
         // Check redirect URI presented matches redirect URI originally used in authorise request
         if ($code->getRedirectUri() !== $redirectUri) {
-            throw new ClientException(
-                sprintf(AuthorizationServer::getExceptionMessage('invalid_request'), 'redirect_uri'),
-                9
-            );
+            throw new Exception\InvalidRequestException('redirect_uri');
         }
 
         $session = $code->getSession();