open failed: EACCES (Permission denied)

Apps targeting Android Q - API 29 by default are given a filtered view into external storage. A quick fix for that is to add this code in the AndroidManifest.xml:

<manifest ... >    <!-- This attribute is "false" by default on apps targeting Android Q. -->    <application android:requestLegacyExternalStorage="true" ... >     ...    </application></manifest>

Read more about it here:https://developer.android.com/training/data-storage/compatibility

For API 23+ you need to request the read/write permissions even if they are already in your manifest.

// Storage Permissionsprivate static final int REQUEST_EXTERNAL_STORAGE = 1;private static String[] PERMISSIONS_STORAGE = {        Manifest.permission.READ_EXTERNAL_STORAGE,        Manifest.permission.WRITE_EXTERNAL_STORAGE};/** * Checks if the app has permission to write to device storage * * If the app does not has permission then the user will be prompted to grant permissions * * @param activity */public static void verifyStoragePermissions(Activity activity) {    // Check if we have write permission    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);    if (permission != PackageManager.PERMISSION_GRANTED) {        // We don't have permission so prompt the user        ActivityCompat.requestPermissions(                activity,                PERMISSIONS_STORAGE,                REQUEST_EXTERNAL_STORAGE        );    }}

AndroidManifest.xml

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

I ran into a similar issue a while back.

Your problem could be in two different areas. It's either how you're creating the file to write to, or your method of writing could be flawed in that it is phone dependent.

If you're writing the file to a specific location on the SD card, try using Environment variables. They should always point to a valid location. Here's an example to write to the downloads folder:

java.io.File xmlFile = new java.io.File(Environment    .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)     + "/Filename.xml");

If you're writing the file to the application's internal storage. Try this example:

java.io.File xmlFile = new java.io.File((getActivity()   .getApplicationContext().getFileStreamPath("FileName.xml")   .getPath()));

Personally I rely on external libraries to handle the streaming to file. This one hasn't failed me yet.

org.apache.commons.io.FileUtils.copyInputStreamToFile(is, file);

I've lost data one too many times on a failed write command, so I rely on well-known and tested libraries for my IO heavy lifting.

If the files are large, you may also want to look into running the IO in the background, or use callbacks.

If you're already using environment variables, it could be a permissions issue. Check out Justin Fiedler's answer below.