There are a number of exceptions issued by the Haystack implementation. They are provided here in table form as reference.
| Exception | Extends | Description |
| BadQueryException | Exception | An exception for a malformed query expression. |
| CannotFindOpenPortException | IOException | When any service attempting to grab a port for communication can't find one. |
| CommunicationException | IOException | When the Middleman can't find an open port. |
| DotfileException | Exception | Exception when trying to archive a dotfile. |
| DuplicateNameException | Exception | HsNameService and HsCommandAPI exception when someone tries to register the same named object. |
| DuplicateURLException | Exception | Exception by the archive process when the user tries to archive the same object |
| HsServiceCloseException | Exception | If any service can't close properly it describes the problem through the HsServiceCloseException |
| HsServiceCriticalInitException | HsServiceInitException | A critical service initialization error. The HaystackRootServer will shut down. |
| HsServiceInitException | Exception | A service initialization error. |
| KeyNotFoundException | Exception | Used when a database type service can't find a certain key. |
| NameNotFoundException | Exception | Used by HsNameService on a getService() request if it can't find the service. |
| NeedleDataException | RuntimeException | If someone tries to place the wrong type of data into a Needle and casting can't fix it. |
| NoSuchStrawException | Exception | If the HsObjectCreatorService can't create the requested Straw because it doesn't exist. |
| OEMGenerateException | Exception | If the HsOEMGenerator gets errors while generating the OEM file. |
| ObjectNotFoundException | Exception | If HsPersistentObjectService doesn't have a specific Straw . |
| SoftlinkException | Exception | If the user tries to archive a softlinked file. |