diff --git a/src/Builder.tsx b/src/Builder.tsx
index c427b8d..e53ef54 100644
--- a/src/Builder.tsx
+++ b/src/Builder.tsx
@@ -28,6 +28,7 @@ const Builder = (props: BuilderPropsWithCallbacks) => {
   const configRegistry = getConfigRegistry()
   const [editorReady, setEditorReady] = useState(false)
   const instanceRef = useRef<BeefreeSDK>(null)
+  const startedRef = useRef(false)
 
   const config = useMemo<IBeeConfig>(() => {
     const configFromRegistry = configRegistry.get(container) || {}
@@ -41,14 +42,18 @@ const Builder = (props: BuilderPropsWithCallbacks) => {
   }, [configRegistry, container, callbacks])
 
   useEffect(() => {
-    if (editorReady) {
-      instanceRef.current?.loadConfig?.(callbacks).catch((error) => {
-        if (error.code === 3001) {
-          callbacksRef.current.onWarning?.(error)
-        } else {
-          callbacksRef.current.onError?.({ code: 1000, message: `Error updating builder config: ${error}` })
-        }
-      })
+    if (editorReady && startedRef.current) {
+      try {
+        instanceRef.current?.loadConfig?.(callbacks).catch((error) => {
+          if (error.code === 3001) {
+            callbacksRef.current.onWarning?.(error)
+          } else {
+            callbacksRef.current.onError?.({ code: 1000, message: `Error updating builder config: ${error}` })
+          }
+        })
+      } catch (error) {
+        callbacksRef.current.onError?.({ code: 1000, message: `Error updating builder config: ${error}` })
+      }
     }
   }, [callbacks, container, editorReady])
 
@@ -73,49 +78,62 @@ const Builder = (props: BuilderPropsWithCallbacks) => {
     }
   }, [token])
 
-  // Creates and starts SDK instance
-  if (instanceRef.current === null && token) {
+  // Construct/start in an effect (not render) so a `disposed` flag in closure
+  // can suppress stale start() resolutions from a prior StrictMode mount —
+  // otherwise loadConfig fires on a not-yet-started instance and throws
+  // "Bee is not started" synchronously from a passive effect.
+  useEffect(() => {
+    if (!token) return
     if (!config.uid) {
       callbacksRef.current.onError?.({
         message: `Can't start the builder without a uid in the config`,
       })
-    } else {
-      instanceRef.current = new BeefreeSDK(token, {
-        beePluginUrl: loaderUrl,
-        ...(process.env.NPM_PACKAGE_NAME && process.env.NPM_PACKAGE_VERSION
-          ? {
-              wrapperInfo: {
-                packageName: process.env.NPM_PACKAGE_NAME,
-                packageVersion: process.env.NPM_PACKAGE_VERSION,
-              },
-            }
-          : {}),
-      })
+      return
+    }
 
-      const beeInstance = instanceRef.current
+    let disposed = false
 
-      if (shared && sessionId) {
-        void beeInstance.join(config, sessionId, bucketDir).then(() => {
-          setEditorReady(true)
-        }).catch((error) => {
-          config.onError?.({
-            message: `Error joining the shared session: ${error}`,
-          })
+    instanceRef.current = new BeefreeSDK(token, {
+      beePluginUrl: loaderUrl,
+      ...(process.env.NPM_PACKAGE_NAME && process.env.NPM_PACKAGE_VERSION
+        ? {
+            wrapperInfo: {
+              packageName: process.env.NPM_PACKAGE_NAME,
+              packageVersion: process.env.NPM_PACKAGE_VERSION,
+            },
+          }
+        : {}),
+    })
+
+    const beeInstance = instanceRef.current
+
+    if (shared && sessionId) {
+      void beeInstance.join(config, sessionId, bucketDir).then(() => {
+        if (disposed) return
+        startedRef.current = true
+        setEditorReady(true)
+      }).catch((error) => {
+        if (disposed) return
+        config.onError?.({
+          message: `Error joining the shared session: ${error}`,
         })
-      } else {
-        void beeInstance.start(config, template, bucketDir, { shared }).then(() => {
-          setEditorReady(true)
-        }).catch((error) => {
-          config.onError?.({
-            message: `Error starting the builder: ${error}`,
-          })
+      })
+    } else {
+      void beeInstance.start(config, template, bucketDir, { shared }).then(() => {
+        if (disposed) return
+        startedRef.current = true
+        setEditorReady(true)
+      }).catch((error) => {
+        if (disposed) return
+        config.onError?.({
+          message: `Error starting the builder: ${error}`,
         })
-      }
+      })
     }
-  }
 
-  useEffect(() => {
     return () => {
+      disposed = true
+      startedRef.current = false
       // SDK doesn't provide a destroy/dispose method, so we manually clean up
       // by clearing the container's content (removes iframe and event listeners)
       const containerElement = document.getElementById(container)
@@ -128,7 +146,8 @@ const Builder = (props: BuilderPropsWithCallbacks) => {
       }
       setEditorReady(false)
     }
-  }, [container])
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [token, container])
 
   return (
     <div