diff --git a/lib/actions/user-actions.js b/lib/actions/user-actions.js
--- a/lib/actions/user-actions.js
+++ b/lib/actions/user-actions.js
@@ -48,8 +48,6 @@
 import type {
   LegacyLogInInfo,
   LegacyLogInResult,
-  LegacyRegisterResult,
-  LegacyRegisterInfo,
   UpdateUserSettingsRequest,
   PolicyAcknowledgmentRequest,
   ClaimUsernameRequest,
@@ -711,47 +709,6 @@
   );
 }
 
-const legacyKeyserverRegisterActionTypes = Object.freeze({
-  started: 'LEGACY_KEYSERVER_REGISTER_STARTED',
-  success: 'LEGACY_KEYSERVER_REGISTER_SUCCESS',
-  failed: 'LEGACY_KEYSERVER_REGISTER_FAILED',
-});
-const legacyKeyserverRegisterCallSingleKeyserverEndpointOptions = {
-  timeout: permissionsAndAuthRelatedRequestTimeout,
-};
-const legacyKeyserverRegister =
-  (
-    callSingleKeyserverEndpoint: CallSingleKeyserverEndpoint,
-  ): ((
-    registerInfo: LegacyRegisterInfo,
-    options?: CallSingleKeyserverEndpointOptions,
-  ) => Promise<LegacyRegisterResult>) =>
-  async (registerInfo, options) => {
-    const deviceTokenUpdateRequest =
-      registerInfo.deviceTokenUpdateRequest[authoritativeKeyserverID()];
-    const { preRequestUserInfo, ...rest } = registerInfo;
-
-    const response = await callSingleKeyserverEndpoint(
-      'create_account',
-      {
-        ...rest,
-        deviceTokenUpdateRequest,
-        platformDetails: getConfig().platformDetails,
-      },
-      {
-        ...legacyKeyserverRegisterCallSingleKeyserverEndpointOptions,
-        ...options,
-      },
-    );
-    return {
-      currentUserInfo: response.currentUserInfo,
-      rawMessageInfos: response.rawMessageInfos,
-      threadInfos: response.cookieChange.threadInfos,
-      userInfos: response.cookieChange.userInfos,
-      calendarQuery: registerInfo.calendarQuery,
-    };
-  };
-
 export type KeyserverAuthInput = $ReadOnly<{
   ...KeyserverAuthInfo,
   +preRequestUserInfo: ?CurrentUserInfo,
@@ -1551,8 +1508,6 @@
   usePrimaryDeviceLogOut,
   useSecondaryDeviceLogOut,
   logOutActionTypes,
-  legacyKeyserverRegister,
-  legacyKeyserverRegisterActionTypes,
   searchUsers,
   searchUsersActionTypes,
   exactSearchUser,
diff --git a/lib/reducers/calendar-filters-reducer.js b/lib/reducers/calendar-filters-reducer.js
--- a/lib/reducers/calendar-filters-reducer.js
+++ b/lib/reducers/calendar-filters-reducer.js
@@ -16,7 +16,6 @@
   keyserverAuthActionTypes,
   deleteKeyserverAccountActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
 } from '../actions/user-actions.js';
 import { extractKeyserverIDFromIDOptional } from '../keyserver-conn/keyserver-call-utils.js';
 import { setNewSessionActionType } from '../keyserver-conn/keyserver-conn-types.js';
@@ -56,8 +55,7 @@
 ): $ReadOnlyArray<CalendarFilter> {
   if (
     action.type === legacyLogInActionTypes.success ||
-    action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success
+    action.type === legacySiweAuthActionTypes.success
   ) {
     return defaultCalendarFilters;
   } else if (
diff --git a/lib/reducers/integrity-reducer.js b/lib/reducers/integrity-reducer.js
--- a/lib/reducers/integrity-reducer.js
+++ b/lib/reducers/integrity-reducer.js
@@ -7,7 +7,6 @@
 import {
   keyserverAuthActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
 } from '../actions/user-actions.js';
 import { extractKeyserverIDFromID } from '../keyserver-conn/keyserver-call-utils.js';
 import {
@@ -63,7 +62,6 @@
   } else if (
     action.type === legacyLogInActionTypes.success ||
     action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success ||
     (action.type === setClientDBStoreActionType &&
       !!action.payload.threadStore &&
       state.threadHashingStatus !== 'completed')
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
@@ -22,7 +22,6 @@
   logOutActionTypes,
   deleteKeyserverAccountActionTypes,
   deleteAccountActionTypes,
-  legacyKeyserverRegisterActionTypes,
   legacyLogInActionTypes,
   restoreUserActionTypes,
 } from '../actions/user-actions.js';
@@ -386,22 +385,6 @@
       keyserverStore: processStoreOps(state, [operation]),
       keyserverStoreOperations: [operation],
     };
-  } else if (action.type === legacyKeyserverRegisterActionTypes.success) {
-    const operation: ReplaceKeyserverOperation = {
-      type: 'replace_keyserver',
-      payload: {
-        id: authoritativeKeyserverID(),
-        keyserverInfo: {
-          ...state.keyserverInfos[authoritativeKeyserverID()],
-          actualizedCalendarQuery: action.payload.calendarQuery,
-          lastCommunicatedPlatformDetails: getConfig().platformDetails,
-        },
-      },
-    };
-    return {
-      keyserverStore: processStoreOps(state, [operation]),
-      keyserverStoreOperations: [operation],
-    };
   } else if (action.type === updateConnectionStatusActionType) {
     const { keyserverID, status } = action.payload;
     if (!state.keyserverInfos[keyserverID]) {
diff --git a/lib/reducers/master-reducer.js b/lib/reducers/master-reducer.js
--- a/lib/reducers/master-reducer.js
+++ b/lib/reducers/master-reducer.js
@@ -31,7 +31,6 @@
 import { legacySiweAuthActionTypes } from '../actions/siwe-actions.js';
 import { fetchPendingUpdatesActionTypes } from '../actions/update-actions.js';
 import {
-  legacyKeyserverRegisterActionTypes,
   legacyLogInActionTypes,
   keyserverAuthActionTypes,
 } from '../actions/user-actions.js';
@@ -104,7 +103,6 @@
     action.type !== incrementalStateSyncActionType &&
     action.type !== fullStateSyncActionType &&
     action.type !== fetchPendingUpdatesActionTypes.success &&
-    action.type !== legacyKeyserverRegisterActionTypes.success &&
     action.type !== legacyLogInActionTypes.success &&
     action.type !== legacySiweAuthActionTypes.success &&
     action.type !== keyserverAuthActionTypes.success &&
diff --git a/lib/reducers/message-reducer.js b/lib/reducers/message-reducer.js
--- a/lib/reducers/message-reducer.js
+++ b/lib/reducers/message-reducer.js
@@ -57,7 +57,6 @@
   keyserverAuthActionTypes,
   deleteKeyserverAccountActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
 } from '../actions/user-actions.js';
 import { setNewSessionActionType } from '../keyserver-conn/keyserver-conn-types.js';
 import {
@@ -1025,18 +1024,6 @@
         newThreadInfos,
       );
     }
-  } else if (action.type === legacyKeyserverRegisterActionTypes.success) {
-    const truncationStatuses: { [string]: MessageTruncationStatus } = {};
-    for (const messageInfo of action.payload.rawMessageInfos) {
-      truncationStatuses[messageInfo.threadID] =
-        messageTruncationStatus.EXHAUSTIVE;
-    }
-    return mergeNewMessages(
-      messageStore,
-      action.payload.rawMessageInfos,
-      truncationStatuses,
-      newThreadInfos,
-    );
   } else if (
     action.type === changeThreadSettingsActionTypes.success ||
     action.type === removeUsersFromThreadActionTypes.success ||
diff --git a/lib/reducers/nav-reducer.js b/lib/reducers/nav-reducer.js
--- a/lib/reducers/nav-reducer.js
+++ b/lib/reducers/nav-reducer.js
@@ -5,7 +5,6 @@
 import {
   identityRegisterActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
   logOutActionTypes,
   deleteAccountActionTypes,
   identityLogInActionTypes,
@@ -27,7 +26,6 @@
   if (
     action.type === legacyLogInActionTypes.started ||
     action.type === legacySiweAuthActionTypes.started ||
-    action.type === legacyKeyserverRegisterActionTypes.started ||
     action.type === fullStateSyncActionType ||
     action.type === incrementalStateSyncActionType
   ) {
diff --git a/lib/reducers/theme-reducer.js b/lib/reducers/theme-reducer.js
--- a/lib/reducers/theme-reducer.js
+++ b/lib/reducers/theme-reducer.js
@@ -2,10 +2,7 @@
 
 import { legacySiweAuthActionTypes } from '../actions/siwe-actions.js';
 import { updateThemeInfoActionType } from '../actions/theme-actions.js';
-import {
-  legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
-} from '../actions/user-actions.js';
+import { legacyLogInActionTypes } from '../actions/user-actions.js';
 import { setNewSessionActionType } from '../keyserver-conn/keyserver-conn-types.js';
 import type { BaseAction } from '../types/redux-types.js';
 import {
@@ -21,8 +18,7 @@
 ): GlobalThemeInfo {
   if (
     action.type === legacyLogInActionTypes.success ||
-    action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success
+    action.type === legacySiweAuthActionTypes.success
   ) {
     return defaultGlobalThemeInfo;
   } else if (
diff --git a/lib/reducers/thread-reducer.js b/lib/reducers/thread-reducer.js
--- a/lib/reducers/thread-reducer.js
+++ b/lib/reducers/thread-reducer.js
@@ -28,7 +28,6 @@
   keyserverAuthActionTypes,
   deleteKeyserverAccountActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
   updateSubscriptionActionTypes,
 } from '../actions/user-actions.js';
 import {
@@ -146,8 +145,7 @@
     );
   } else if (
     action.type === legacyLogInActionTypes.success ||
-    action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success
+    action.type === legacySiweAuthActionTypes.success
   ) {
     const newThreadInfos = action.payload.threadInfos;
     const threadStoreOperations = [
diff --git a/lib/reducers/user-reducer.js b/lib/reducers/user-reducer.js
--- a/lib/reducers/user-reducer.js
+++ b/lib/reducers/user-reducer.js
@@ -20,7 +20,6 @@
   keyserverAuthActionTypes,
   logOutActionTypes,
   legacyLogInActionTypes,
-  legacyKeyserverRegisterActionTypes,
   setUserSettingsActionTypes,
   updateUserAvatarActionTypes,
   restoreUserActionTypes,
@@ -92,7 +91,6 @@
   } else if (
     action.type === legacyLogInActionTypes.success ||
     action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success ||
     action.type === logOutActionTypes.success ||
     action.type === deleteAccountActionTypes.success
   ) {
@@ -452,8 +450,7 @@
     }
   } else if (
     action.type === legacyLogInActionTypes.success ||
-    action.type === legacySiweAuthActionTypes.success ||
-    action.type === legacyKeyserverRegisterActionTypes.success
+    action.type === legacySiweAuthActionTypes.success
   ) {
     const newUserInfos = _keyBy(userInfo => userInfo.id)(
       action.payload.userInfos,
diff --git a/lib/types/account-types.js b/lib/types/account-types.js
--- a/lib/types/account-types.js
+++ b/lib/types/account-types.js
@@ -51,12 +51,6 @@
   +currentUserInfo: LoggedOutUserInfo,
 };
 
-export type LegacyRegisterInfo = {
-  ...LegacyLogInExtraInfo,
-  +username: string,
-  +password: string,
-};
-
 export type DeviceTokenUpdateRequest = {
   +deviceToken: string,
 };
@@ -87,14 +81,6 @@
   },
 };
 
-export type LegacyRegisterResult = {
-  +currentUserInfo: LoggedInUserInfo,
-  +rawMessageInfos: $ReadOnlyArray<RawMessageInfo>,
-  +threadInfos: RawThreadInfos,
-  +userInfos: $ReadOnlyArray<UserInfo>,
-  +calendarQuery: CalendarQuery,
-};
-
 export const recoveryFromReduxActionSources = Object.freeze({
   cookieInvalidationResolutionAttempt: 'COOKIE_INVALIDATION_RESOLUTION_ATTEMPT',
   appStartCookieLoggedInButInvalidRedux:
diff --git a/lib/types/redux-types.js b/lib/types/redux-types.js
--- a/lib/types/redux-types.js
+++ b/lib/types/redux-types.js
@@ -7,7 +7,6 @@
   KeyserverLogOutResult,
   LegacyLogInStartingPayload,
   LegacyLogInResult,
-  LegacyRegisterResult,
   DefaultNotificationPayload,
   ClaimUsernameResponse,
   KeyserverAuthResult,
@@ -450,22 +449,6 @@
         +payload: LegacyLogInResult,
         +loadingInfo: LoadingInfo,
       }
-    | {
-        +type: 'LEGACY_KEYSERVER_REGISTER_STARTED',
-        +loadingInfo: LoadingInfo,
-        +payload: LegacyLogInStartingPayload,
-      }
-    | {
-        +type: 'LEGACY_KEYSERVER_REGISTER_FAILED',
-        +error: true,
-        +payload: Error,
-        +loadingInfo: LoadingInfo,
-      }
-    | {
-        +type: 'LEGACY_KEYSERVER_REGISTER_SUCCESS',
-        +payload: LegacyRegisterResult,
-        +loadingInfo: LoadingInfo,
-      }
     | {
         +type: 'IDENTITY_REGISTER_STARTED',
         +payload?: void,