diff --git a/lib/reducers/keyserver-reducer.js b/lib/reducers/keyserver-reducer.js
--- a/lib/reducers/keyserver-reducer.js
+++ b/lib/reducers/keyserver-reducer.js
@@ -20,6 +20,7 @@
 } from '../actions/user-actions.js';
 import { queueActivityUpdatesActionType } from '../types/activity-types.js';
 import type { KeyserverInfos, KeyserverStore } from '../types/keyserver-types';
+import { defaultKeyserverInfo } from '../types/keyserver-types.js';
 import type { BaseAction } from '../types/redux-types.js';
 import {
   fullStateSyncActionType,
@@ -75,14 +76,22 @@
       keyserverInfos,
     };
   } else if (action.type === setNewSessionActionType) {
-    const { keyserverID } = action.payload;
+    const { keyserverID, urlPrefix } = action.payload;
+    let previousEntry = state.keyserverInfos[keyserverID];
+    if (!previousEntry) {
+      previousEntry = {
+        ...defaultKeyserverInfo,
+        urlPrefix,
+      };
+    }
+
     if (action.payload.sessionChange.cookie !== undefined) {
       state = {
         ...state,
         keyserverInfos: {
           ...state.keyserverInfos,
           [keyserverID]: {
-            ...state.keyserverInfos[keyserverID],
+            ...previousEntry,
             cookie: action.payload.sessionChange.cookie,
           },
         },
@@ -94,7 +103,7 @@
         keyserverInfos: {
           ...state.keyserverInfos,
           [keyserverID]: {
-            ...state.keyserverInfos[keyserverID],
+            ...previousEntry,
             connection: {
               ...state.keyserverInfos[keyserverID].connection,
               queuedActivityUpdates: [],
diff --git a/lib/socket/socket.react.js b/lib/socket/socket.react.js
--- a/lib/socket/socket.react.js
+++ b/lib/socket/socket.react.js
@@ -506,6 +506,7 @@
             logInActionSource:
               logInActionSources.socketAuthErrorResolutionAttempt,
             keyserverID: ashoatKeyserverID,
+            urlPrefix: this.props.urlPrefix,
           },
         });
       }
@@ -642,6 +643,7 @@
             error: null,
             logInActionSource: undefined,
             keyserverID: ashoatKeyserverID,
+            urlPrefix: this.props.urlPrefix,
           },
         });
       }
diff --git a/lib/types/session-types.js b/lib/types/session-types.js
--- a/lib/types/session-types.js
+++ b/lib/types/session-types.js
@@ -83,6 +83,7 @@
   +error: ?string,
   +logInActionSource: ?LogInActionSource,
   +keyserverID: string,
+  +urlPrefix: string,
 };
 
 export type SessionState = {
diff --git a/lib/utils/action-utils.js b/lib/utils/action-utils.js
--- a/lib/utils/action-utils.js
+++ b/lib/utils/action-utils.js
@@ -172,6 +172,7 @@
   error: ?string,
   logInActionSource: ?LogInActionSource,
   keyserverID: string,
+  urlPrefix: string,
 ) {
   dispatch({
     type: setNewSessionActionType,
@@ -181,6 +182,7 @@
       error,
       logInActionSource,
       keyserverID,
+      urlPrefix,
     },
   });
 }
@@ -221,6 +223,7 @@
         error,
         logInActionSource,
         keyserverID,
+        urlPrefix,
       );
     };
     try {
@@ -327,6 +330,7 @@
       error,
       undefined,
       keyserverID,
+      urlPrefix,
     );
   // This function gets called before callServerEndpoint sends a request,
   // to make sure that we're not in the middle of trying to recover