diff --git a/juju/errors.py b/juju/errors.py
index de52174..da11cdb 100644
--- a/juju/errors.py
+++ b/juju/errors.py
@@ -1,5 +1,16 @@
 class JujuError(Exception):
-    pass
+    def __init__(self, *args, **kwargs):
+        self.message = ''
+        self.errors = []
+        if args:
+            self.message = str(args[0])
+            if isinstance(args[0], (list, tuple)):
+                self.errors = args[0]
+            elif len(args) > 1:
+                self.errors = list(args)
+            else:
+                self.errors = [self.message]
+        super().__init__(*args, **kwargs)
 
 
 class JujuAPIError(JujuError):
@@ -14,3 +25,25 @@
 
 class JujuConnectionError(ConnectionError, JujuError):
     pass
+
+
+class JujuAuthError(JujuConnectionError):
+    pass
+
+
+class JujuRedirectException(Exception):
+    """Exception indicating that a redirection was requested"""
+    def __init__(self, redirect_info):
+        self.redirect_info = redirect_info
+
+    @property
+    def ca_cert(self):
+        return self.redirect_info['ca-cert']
+
+    @property
+    def endpoints(self):
+        return [
+            ('{value}:{port}'.format(**s), self.ca_cert)
+            for servers in self.redirect_info['servers']
+            for s in servers if s['scope'] == 'public'
+        ]