diff --git a/cast/src/receiver/layout/hc-main.ts b/cast/src/receiver/layout/hc-main.ts
index 876b68cda3..dcf7a80eec 100644
--- a/cast/src/receiver/layout/hc-main.ts
+++ b/cast/src/receiver/layout/hc-main.ts
@@ -205,7 +205,6 @@ export class HcMain extends HassElement {
           expires_in: 0,
         }),
       });
-      this._hassUUID = msg.hassUUID;
     } catch (err: any) {
       const errorMessage = this._getErrorMessage(err);
       this._error = errorMessage;
@@ -225,6 +224,17 @@ export class HcMain extends HassElement {
       this.hass.connection.close();
     }
     this.initializeHass(auth, connection);
+    if (this._hassUUID !== msg.hassUUID) {
+      this._hassUUID = msg.hassUUID;
+      this._lovelacePath = null;
+      this._urlPath = undefined;
+      this._lovelaceConfig = undefined;
+      if (this._unsubLovelace) {
+        this._unsubLovelace();
+        this._unsubLovelace = undefined;
+      }
+      resourcesLoaded = false;
+    }
     this._error = undefined;
     this._sendStatus();
   }
@@ -233,7 +243,7 @@ export class HcMain extends HassElement {
     this._showDemo = false;
     // We should not get this command before we are connected.
     // Means a client got out of sync. Let's send status to them.
-    if (!this.hass) {
+    if (!this.hass?.connected) {
       this._sendStatus(msg.senderId!);
       this._error = "Cannot show Lovelace because we're not connected.";
       this._sendError(
@@ -284,6 +294,7 @@ export class HcMain extends HassElement {
       this._lovelaceConfig = undefined;
       if (this._unsubLovelace) {
         this._unsubLovelace();
+        this._unsubLovelace = undefined;
       }
       const llColl = atLeastVersion(this.hass.connection.haVersion, 0, 107)
         ? getLovelaceCollection(this.hass.connection, msg.urlPath)
diff --git a/src/common/dom/apply_themes_on_element.ts b/src/common/dom/apply_themes_on_element.ts
index a6fd07b5b3..cf431b6cb8 100644
--- a/src/common/dom/apply_themes_on_element.ts
+++ b/src/common/dom/apply_themes_on_element.ts
@@ -41,7 +41,9 @@ export const applyThemesOnElement = (
   // If there is no explicitly desired dark mode provided, we automatically
   // use the active one from `themes`.
   const darkMode =
-    themeSettings?.dark !== undefined ? themeSettings.dark : themes.darkMode;
+    themeSettings?.dark !== undefined
+      ? themeSettings.dark
+      : themes?.darkMode || false;
 
   let cacheKey = themeToApply;
   let themeRules: Partial<ThemeVars> = {};