diff --git a/packages/puter-js/src/index.js b/packages/puter-js/src/index.js
index 1cccd388..6c2282eb 100644
--- a/packages/puter-js/src/index.js
+++ b/packages/puter-js/src/index.js
@@ -112,10 +112,11 @@ window.puter = (function() {
             // The default APIOrigin is https://api.puter.com. However, if the URL contains a `puter.api_origin` query parameter,
             // then that value is used as the APIOrigin. If the URL contains a `puter.domain` query parameter, then the APIOrigin
             // is constructed as `https://api.<puter.domain>`.
+            // This should only be done when the SDK is running in 'app' mode.
             this.APIOrigin = this.defaultAPIOrigin;
-            if(URLParams.has('puter.api_origin')){
+            if(URLParams.has('puter.api_origin') && this.env === 'app'){
                 this.APIOrigin = decodeURIComponent(URLParams.get('puter.api_origin'));
-            }else if(URLParams.has('puter.domain')){
+            }else if(URLParams.has('puter.domain') && this.env === 'app'){
                 this.APIOrigin = 'https://api.' + URLParams.get('puter.domain');
             }
 
diff --git a/src/IPC.js b/src/IPC.js
index a71b2149..a5e3ffdf 100644
--- a/src/IPC.js
+++ b/src/IPC.js
@@ -71,7 +71,10 @@ window.addEventListener('message', async (event) => {
 
     // `appInstanceID` is required
     if(!event.data.appInstanceID){
-        console.log(`appInstanceID is needed`);
+        console.error(`appInstanceID is needed`);
+        return;
+    }else if(!window.app_instance_ids.has(event.data.appInstanceID)){
+        console.error(`appInstanceID is invalid`);
         return;
     }
 
@@ -165,7 +168,6 @@ window.addEventListener('message', async (event) => {
                 center: event.data.options.center,
                 show_in_taskbar: event.data.options.show_in_taskbar,                    
                 iframe_srcdoc: event.data.options.content,
-                iframe_url: event.data.options.url,
                 parent_uuid: event.data.appInstanceID,
             })
         }
diff --git a/src/globals.js b/src/globals.js
index ea429a28..3860f921 100644
--- a/src/globals.js
+++ b/src/globals.js
@@ -24,6 +24,7 @@ window.window_nav_history = {};
 window.window_nav_history_current_position = {};
 window.progress_tracker = [];
 window.upload_item_global_id = 0;
+window.app_instance_ids = new Set();
 
 window.download_progress = [];
 window.download_item_global_id = 0;
diff --git a/src/helpers.js b/src/helpers.js
index f912f1b8..7b3ecfed 100644
--- a/src/helpers.js
+++ b/src/helpers.js
@@ -1762,6 +1762,10 @@ window.launch_app = async (options)=>{
         // ...and finally append utm_source=puter.com to the URL
         iframe_url.searchParams.append('utm_source', 'puter.com');
 
+        // register app_instance_uid
+        window.app_instance_ids.add(uuid);
+
+        // open window
         el_win = UIWindow({
             element_uuid: uuid,
             title: title,