android - java.lang.IllegalStateException: No tab known for tag null for FragmentTabHost -

i getting error while rendering xml file. has fragmenttabhost, tabwidget vertical scrollview , framelayout displaying tab's content. , ya using vertical tabs on horizontal.

below layout file

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="@color/background2"     android:orientation="vertical">      <include         android:id="@+id/toolbar"         layout="@layout/toolbar" />      <android.support.v4.app.fragmenttabhost         android:id="@android:id/tabhost"         android:layout_width="match_parent"         android:layout_height="0dp"         android:layout_weight="1">          <linearlayout             android:layout_width="match_parent"             android:layout_height="match_parent"             android:orientation="horizontal"             android:weightsum="1">              <scrollview                 android:layout_width="0dp"                 android:layout_height="wrap_content"                 android:layout_weight="0.3">                  <tabwidget                     android:id="@android:id/tabs"                     android:layout_width="match_parent"                     android:layout_height="wrap_content" />              </scrollview>              <framelayout                 android:id="@android:id/tabcontent"                 android:layout_width="0dp"                 android:layout_height="0dp"                 android:layout_weight="0" />              <framelayout                 android:id="@+id/realtabcontent"                 android:layout_width="0dp"                 android:layout_height="match_parent"                 android:layout_weight="0.7" />         </linearlayout>     </android.support.v4.app.fragmenttabhost>      <linearlayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:minheight="@dimen/standard_height"         android:orientation="horizontal"         android:weightsum="1">          <com.custom.fontbutton             android:id="@+id/btn_clear"             android:layout_width="0dp"             android:layout_height="wrap_content"             android:layout_weight="0.3"             android:background="@color/toolbar"             android:minheight="@dimen/standard_height"             android:text="clear"             android:textcolor="@color/background"             android:textsize="@dimen/font_18"             app:customfont="@string/font_regular" />          <com.custom.fontbutton             android:id="@+id/btn_apply"             android:layout_width="0dp"             android:layout_height="wrap_content"             android:layout_weight="0.7"             android:background="@color/button"             android:elevation="5dp"             android:minheight="@dimen/standard_height"             android:text="apply"             android:textcolor="@color/background"             android:textsize="@dimen/font_18"             app:customfont="@string/font_regular" />      </linearlayout>   </linearlayout> 

and error throwing while rendering -

java.lang.illegalstateexception: no tab known tag null     @ android.support.v4.app.fragmenttabhost.dotabchanged(fragmenttabhost.java:330)     @ android.support.v4.app.fragmenttabhost.onattachedtowindow(fragmenttabhost.java:280)     @ android.view.view.dispatchattachedtowindow(view.java:14514)     @ android.view.viewgroup.dispatchattachedtowindow(viewgroup.java:2836)     @ android.view.viewgroup.dispatchattachedtowindow(viewgroup.java:2843)     @ android.view.viewgroup.dispatchattachedtowindow(viewgroup.java:2843)     @ android.view.viewgroup.dispatchattachedtowindow(viewgroup.java:2843)     @ android.view.attachinfo_accessor.setattachinfo(attachinfo_accessor.java:42)     @ com.android.layoutlib.bridge.impl.rendersessionimpl.inflate(rendersessionimpl.java:232)     @ com.android.layoutlib.bridge.bridge.createsession(bridge.java:426)     @ com.android.ide.common.rendering.layoutlibrary.createsession(layoutlibrary.java:350)     @ com.android.tools.idea.rendering.rendertask$2.compute(rendertask.java:510)     @ com.android.tools.idea.rendering.rendertask$2.compute(rendertask.java:498)     @ com.intellij.openapi.application.impl.applicationimpl.runreadaction(applicationimpl.java:888)     @ com.android.tools.idea.rendering.rendertask.createrendersession(rendertask.java:498)     @ com.android.tools.idea.rendering.rendertask.access$600(rendertask.java:72)     @ com.android.tools.idea.rendering.rendertask$3.call(rendertask.java:610)     @ com.android.tools.idea.rendering.rendertask$3.call(rendertask.java:607)     @ com.android.tools.idea.rendering.renderservice.runrenderaction(renderservice.java:366)     @ com.android.tools.idea.rendering.rendertask.render(rendertask.java:607)     @ com.android.tools.idea.rendering.rendertask.render(rendertask.java:629)     @ com.intellij.android.designer.designsurface.androiddesignereditorpanel$6.run(androiddesignereditorpanel.java:480)     @ com.intellij.util.ui.update.mergingupdatequeue.execute(mergingupdatequeue.java:320)     @ com.intellij.util.ui.update.mergingupdatequeue.execute(mergingupdatequeue.java:310)     @ com.intellij.util.ui.update.mergingupdatequeue$2.run(mergingupdatequeue.java:254)     @ com.intellij.util.ui.update.mergingupdatequeue.flush(mergingupdatequeue.java:269)     @ com.intellij.util.ui.update.mergingupdatequeue.flush(mergingupdatequeue.java:227)     @ com.intellij.util.ui.update.mergingupdatequeue.run(mergingupdatequeue.java:217)     @ com.intellij.util.concurrency.queueprocessor.runsafely(queueprocessor.java:238)     @ com.intellij.util.alarm$request$1.run(alarm.java:351)     @ java.util.concurrent.executors$runnableadapter.call(executors.java:439)     @ java.util.concurrent.futuretask$sync.innerrun(futuretask.java:303)     @ java.util.concurrent.futuretask.run(futuretask.java:138)     @ java.util.concurrent.threadpoolexecutor$worker.runtask(threadpoolexecutor.java:895)     @ java.util.concurrent.threadpoolexecutor$worker.run(threadpoolexecutor.java:918)     @ java.lang.thread.run(thread.java:695) 

ps: have read other post, none of them working, please don't mark duplicate.

edit: solution found

the problem fragmenttabhost default orientation set tabwidget.horizontal , cannot modified via xml, why illegalstateexception occurred vertical scrolls. overcome in fragment or activity class need set orientation manually. check out snippet setting orientation

tabwidget.setorientation(tabwidget.vertical); 

once done done error!