# Exceptions
<a name="query-exceptions"></a>

The following table lists query-side exceptions that could be encountered while using a query.


| Neptune Analytics error code | HTTP status | Retriable | Description | 
| --- | --- | --- | --- | 
| Validation Exception | 400 | No | Something is wrong with the required information - Eg. a malformed query. | 
| AccessDeniedException | 403 | No | User is not authorized to perform the requested operation. | 
| ResourceNotFoundException | 404 | No | Requested resource is not available. | 
| ThrottlingException | 429 | Yes | The server has received too many concurrent requests. | 
| InternalServerErrorException | 500 | Yes | The server failed to process the request for an unknown reason. | 
| UnprocessableException | 422 | No | Request cannot be processed due to known reasons - Eg. The query timed out. | 
| ConflictException | 409 | Yes | Concurrently running queries attempted to modify resources or data records concurrently and the conflict could not be resolved automatically. Please retry with an exponential back-off strategy. |