the app throws FileNotFoundException when clicking "USE EXPORT LOCATION" button

[androidAppGuard]

the environment is as follows:

App version: v0.21.4
Android version: 6.0
Device: Nexux_5X

The steps to reproduce:

The exception log is as follows:

05-13 05:50:37.172 9200-9200/protect.budgetwatch E/BudgetWatch: Could not import file /storage/emulated/0/BudgetWatch.csv
    java.io.FileNotFoundException: /storage/emulated/0/BudgetWatch.csv: open failed: ENOENT (No such file or directory)
        at libcore.io.IoBridge.open(IoBridge.java:452)
        at java.io.FileInputStream.<init>(FileInputStream.java:76)
        at protect.budgetwatch.ImportExportActivity$5.onClick(ImportExportActivity.java:239)
        at android.view.View.performClick(View.java:5198)
        at android.view.View$PerformClick.run(View.java:21147)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
        at libcore.io.Posix.open(Native Method)
        at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
        at libcore.io.IoBridge.open(IoBridge.java:438)
        at java.io.FileInputStream.<init>(FileInputStream.java:76) 
        at protect.budgetwatch.ImportExportActivity$5.onClick(ImportExportActivity.java:239) 
        at android.view.View.performClick(View.java:5198) 
        at android.view.View$PerformClick.run(View.java:21147) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)