diff --git a/src/zen/sessionstore/ZenSessionManager.sys.mjs b/src/zen/sessionstore/ZenSessionManager.sys.mjs
index 724087d98..176d4a102 100644
--- a/src/zen/sessionstore/ZenSessionManager.sys.mjs
+++ b/src/zen/sessionstore/ZenSessionManager.sys.mjs
@@ -142,7 +142,11 @@ export class nsZenSessionManager {
     // gotten the opportunity to save the session yet.
     if (!Services.prefs.getBoolPref(MIGRATION_PREF, false)) {
       Services.prefs.setBoolPref(MIGRATION_PREF, true);
-      for (const winData of initialState.windows || []) {
+      this.#sidebar = {
+        ...this.#sidebar,
+        spaces: this._migrationSpaceData || [],
+      };
+      for (const winData of initialState?.windows || []) {
         winData.spaces = this._migrationSpaceData || [];
       }
       delete this._migrationSpaceData;
diff --git a/src/zen/workspaces/ZenWorkspaces.mjs b/src/zen/workspaces/ZenWorkspaces.mjs
index 9b3941cc9..92eea4991 100644
--- a/src/zen/workspaces/ZenWorkspaces.mjs
+++ b/src/zen/workspaces/ZenWorkspaces.mjs
@@ -850,10 +850,10 @@ class nsZenWorkspaces {
     return this._workspaceCache;
   }
 
-  async restoreWorkspacesFromSessionStore(aWinData) {
-    this._workspaceCache = aWinData.spaces || [
-      await this.createAndSaveWorkspace('Space', undefined, true),
-    ];
+  async restoreWorkspacesFromSessionStore(aWinData = {}) {
+    this._workspaceCache = aWinData.spaces?.length
+      ? aWinData.spaces
+      : [await this.createAndSaveWorkspace('Space', undefined, true)];
     this.activeWorkspace = aWinData.activeZenSpace || this._workspaceCache[0].uuid;
     await this.initializeWorkspaces();
     this.#hasInitialized = true;
diff --git a/src/zen/workspaces/ZenWorkspacesStorage.mjs b/src/zen/workspaces/ZenWorkspacesStorage.mjs
index 63097e240..80c7a82e5 100644
--- a/src/zen/workspaces/ZenWorkspacesStorage.mjs
+++ b/src/zen/workspaces/ZenWorkspacesStorage.mjs
@@ -26,8 +26,7 @@ window.ZenWorkspaceBookmarksStorage = {
           workspace_uuid TEXT NOT NULL,
           created_at INTEGER NOT NULL,
           updated_at INTEGER NOT NULL,
-          UNIQUE(bookmark_guid, workspace_uuid),
-          FOREIGN KEY(workspace_uuid) REFERENCES zen_workspaces(uuid) ON DELETE CASCADE,
+          UNIQUE(bookmark_guid),
           FOREIGN KEY(bookmark_guid) REFERENCES moz_bookmarks(guid) ON DELETE CASCADE
           )
       `);
@@ -46,8 +45,7 @@ window.ZenWorkspaceBookmarksStorage = {
           workspace_uuid TEXT NOT NULL,
           change_type TEXT NOT NULL,
           timestamp INTEGER NOT NULL,
-          UNIQUE(bookmark_guid, workspace_uuid),
-          FOREIGN KEY(workspace_uuid) REFERENCES zen_workspaces(uuid) ON DELETE CASCADE,
+          UNIQUE(bookmark_guid),
           FOREIGN KEY(bookmark_guid) REFERENCES moz_bookmarks(guid) ON DELETE CASCADE
           )
       `);