--- a
+++ b/qiita_pet/exceptions.py
@@ -0,0 +1,34 @@
+# -----------------------------------------------------------------------------
+# Copyright (c) 2014--, The Qiita Development Team.
+#
+# Distributed under the terms of the BSD 3-clause License.
+#
+# The full license is in the file LICENSE, distributed with this software.
+# -----------------------------------------------------------------------------
+from tornado.web import HTTPError
+
+from qiita_core.exceptions import QiitaError
+
+
+class QiitaHTTPError(HTTPError):
+    def __init__(self, status_code=500, log_message=None, *args, **kwargs):
+        super(QiitaHTTPError, self).__init__(
+            status_code, log_message, *args, **kwargs)
+        # The HTTPError has an attribute named "reason" that will get send to
+        # the requester if specified. However, the developer need to
+        # specifically pass the keyword "reason" when raising the exception.
+        # The vast majority of our code it is not using the keyword "reason"
+        # but we are using "log_message". By setting up the attribute reason
+        # with the value in log_message, we make sure that when the answer
+        # is sent to the requester, it will contain a useful error message,
+        # rather than a generic error message.
+        if not self.reason:
+            self.reason = log_message
+
+
+class QiitaPetAuthorizationError(QiitaError):
+    """When a user tries to access a resource without proper authorization"""
+    def __init__(self, user_id, resource_name_str):
+        super(QiitaPetAuthorizationError, self).__init__()
+        self.args = ("User %s is not authorized to access %s"
+                     % (user_id, resource_name_str),)