diff --git a/peer/peerdata.py b/peer/peerdata.py
index d1bcf6f3..40676e88 100644
--- a/peer/peerdata.py
+++ b/peer/peerdata.py
@@ -28,4 +28,5 @@ class PeerData(IPeerData):
     def get_metadata(self, key):
         if key in self.metadata:
             return self.metadata[key], None
-        return None, "key not found"
+        else:
+            raise Exception("key not found")
diff --git a/peer/peerdata_interface.py b/peer/peerdata_interface.py
index f7e8b5df..1d5fa8ca 100644
--- a/peer/peerdata_interface.py
+++ b/peer/peerdata_interface.py
@@ -41,7 +41,8 @@ class IPeerData(ABC):
 
     """
     :param key: key in KV pair
-    :return: val for key, error (only defined if key not found)
+    :return: val for key
+    :raise Exception: key not found exception
     """
     def get_metadata(self, key):
         pass
diff --git a/peer/peerstore.py b/peer/peerstore.py
index 3922b7f5..58f195db 100644
--- a/peer/peerstore.py
+++ b/peer/peerstore.py
@@ -32,8 +32,9 @@ class PeerStore(IPeerStore):
 
     def get_protocols(self, peer_id):
         if peer_id in self.peer_map:
-            return self.peer_map[peer_id].get_protocols(), None
-        return None, peer_id + " not found"
+            return self.peer_map[peer_id].get_protocols()
+        else:
+            raise Exception("peer ID not found")
 
     def add_protocols(self, peer_id, protocols):
         peer = self.__create_or_get_peer(peer_id)
@@ -44,9 +45,10 @@ class PeerStore(IPeerStore):
 
     def get(self, peer_id, key):
         if peer_id in self.peer_map:
-            val, error = self.peer_map[peer_id].get_metadata(key)
-            return val, error
-        return None, peer_id + " not found"
+            val = self.peer_map[peer_id].get_metadata(key)
+            return val
+        else:
+            raise Exception("peer ID not found")
 
     def put(self, peer_id, key, val):
         # <<?>>
@@ -64,8 +66,9 @@ class PeerStore(IPeerStore):
 
     def addrs(self, peer_id):
         if peer_id in self.peer_map:
-            return self.peer_map[peer_id].get_addrs(), None
-        return None, peer_id + " not found"
+            return self.peer_map[peer_id].get_addrs()
+        else:
+            raise Exception("peer ID not found")
 
     def clear_addrs(self, peer_id):
         # Only clear addresses if the peer is in peer map
diff --git a/peer/peerstore_interface.py b/peer/peerstore_interface.py
index 67f75c1d..8615ce05 100644
--- a/peer/peerstore_interface.py
+++ b/peer/peerstore_interface.py
@@ -20,7 +20,8 @@ class IPeerStore(ABC, IAddrBook, IPeerMetadata):
     def get_protocols(self, peer_id):
         """
         :param peer_id: peer ID to get protocols for
-        :return: protocols (as strings), error
+        :return: protocols (as strings)
+        :raise Exception: peer ID not found exception
         """
         pass
 
@@ -29,7 +30,7 @@ class IPeerStore(ABC, IAddrBook, IPeerMetadata):
         """
         :param peer_id: peer ID to add protocols for
         :param protocols: protocols to add
-        :return: error
+        :raise Exception: peer ID not found exception
         """
         pass
 
@@ -38,7 +39,7 @@ class IPeerStore(ABC, IAddrBook, IPeerMetadata):
         """
         :param peer_id: peer ID to set protocols for
         :param protocols: protocols to set
-        :return: error
+        :raise Exception: peer ID not found exception
         """
         pass