Androidの the loading of difficult diseases report error inflating class <unknown>

Android.view.InflateException:Binary XML file line #12: Error inflating class <unknown>

It is possible that there is an error in the property of one of the wedget in your layout, such as a reference to attr/xxxx, but there is no value assigned to this attr in your subject.

<?XML version= "1.0" encoding= "Utf-8"?><LinearLayoutxmlns:android= "Http://schemas.android.com/apk/res/android"Android:id= "@+id/llplaceholderloading"Android:layout_width= "Match_parent"Android:layout_height= "Match_parent"android:layout_gravity= "Center"Android:background= "? Attr/primary_page_background"android:gravity= "Center"android:orientation= "vertical"android:visibility= "visible" >    <ProgressBarstyle= "@style/apptheme.widget.progress"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:layout_marginbottom= "8DP" />    <TextViewAndroid:id= "@+id/tvloadtip"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:layout_marginbottom= "16DP"Android:text= "? Attr/loading_tip"Android:textcolor= "@color/progress_tips_text_color"android:textappearance= "? Android:attr/textappearancemedium" /></LinearLayout>

Like this in style does not have the attr assignment, this interface is loaded well, and error

02-03 17:24:50.746:e/androidruntime (10702): java.lang.RuntimeException:Unable to start activity componentinfo{ Net.realtor.app.extranet.cmls/net.realtor.app.extranet.cmls.ui.activity.testactivity}: Android.view.InflateException:Binary XML file line #12: Error inflating class Android.widget.ProgressBar

Androidの the loading of difficult diseases report error inflating class <unknown>