diff --git a/src/btn.ts b/src/btn.ts
index 63b30c6..4d3e162 100644
--- a/src/btn.ts
+++ b/src/btn.ts
@@ -1,5 +1,6 @@
 
 import { loadMscore, WebMscore } from './mscore'
+import { useTimeout } from './utils'
 import i18n from './i18n'
 // @ts-ignore
 import btnListCss from './btn.css'
@@ -159,13 +160,13 @@ export namespace BtnAction {
     })
   }
 
-  export const download = (url: UrlInput): BtnAction => {
-    return process(async (): Promise<any> => {
+  export const download = (url: UrlInput, fallback?: () => Promisable<void>, timeout?: number): BtnAction => {
+    return process(async (): Promise<void> => {
       const _url = await normalizeUrlInput(url)
       const a = document.createElement('a')
       a.href = _url
       a.dispatchEvent(new MouseEvent('click'))
-    })
+    }, fallback, timeout)
   }
 
   export const mscoreWindow = (fn: (w: Window, score: WebMscore, processingTextEl: ChildNode) => any): BtnAction => {
@@ -199,7 +200,7 @@ export namespace BtnAction {
     }
   }
 
-  export const process = (fn: () => any): BtnAction => {
+  export const process = (fn: () => any, fallback?: () => Promisable<void>, timeout = Infinity): BtnAction => {
     return async (name, btn, setText): Promise<void> => {
       const _onclick = btn.onclick
 
@@ -207,11 +208,17 @@ export namespace BtnAction {
       setText(i18n('PROCESSING')())
 
       try {
-        await fn()
+        await useTimeout(fn(), timeout)
         setText(name)
       } catch (err) {
-        setText(i18n('BTN_ERROR')())
         console.error(err)
+        if (fallback) {
+          // use fallback
+          await fallback()
+          setText(name)
+        } else {
+          setText(i18n('BTN_ERROR')())
+        }
       }
 
       btn.onclick = _onclick
diff --git a/src/main.ts b/src/main.ts
index 9cbce7c..060e062 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -13,6 +13,12 @@ const main = (): void => {
   const btnList = new BtnList()
   const filename = scoreinfo.fileName
 
+  let indvPartBtn: HTMLButtonElement | null = null
+  const fallback = () => {
+    // btns fallback to load from MSCZ file (`Individual Parts`)
+    return indvPartBtn?.click()
+  }
+
   btnList.add({
     name: i18n('DOWNLOAD')('MSCZ'),
     action: BtnAction.process(downloadMscz),
@@ -20,7 +26,7 @@ const main = (): void => {
 
   btnList.add({
     name: i18n('DOWNLOAD')('PDF'),
-    action: BtnAction.process(downloadPDF),
+    action: BtnAction.process(downloadPDF, fallback, 3 * 60 * 1000 /* 3min */),
   })
 
   btnList.add({
@@ -35,15 +41,15 @@ const main = (): void => {
 
   btnList.add({
     name: i18n('DOWNLOAD')('MIDI'),
-    action: BtnAction.download(() => getFileUrl('midi')),
+    action: BtnAction.download(() => getFileUrl('midi'), fallback, 30 * 1000 /* 30s */),
   })
 
   btnList.add({
     name: i18n('DOWNLOAD')('MP3'),
-    action: BtnAction.download(() => getFileUrl('mp3')),
+    action: BtnAction.download(() => getFileUrl('mp3'), fallback, 30 * 1000 /* 30s */),
   })
 
-  btnList.add({
+  indvPartBtn = btnList.add({
     name: i18n('IND_PARTS')(),
     tooltip: i18n('IND_PARTS_TOOLTIP')(),
     action: BtnAction.mscoreWindow(async (w, score, txt) => {
diff --git a/src/utils.ts b/src/utils.ts
index ee5b88e..2665295 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -19,6 +19,19 @@ export const fetchData = async (url: string, init?: RequestInit): Promise<Uint8A
   return new Uint8Array(data)
 }
 
+export const useTimeout = async <T> (promise: T | Promise<T>, ms: number): Promise<T> => {
+  if (!(promise instanceof Promise)) {
+    return promise
+  }
+
+  return new Promise((resolve, reject) => {
+    const i = setTimeout(() => {
+      reject(new Error('timeout'))
+    }, ms)
+    promise.then(resolve, reject).finally(() => clearTimeout(i))
+  })
+}
+
 export const waitForDocumentLoaded = (): Promise<void> => {
   if (document.readyState !== 'complete') {
     return new Promise(resolve => {