rn-fetch-blob: Android: "Permission denied" – no matter what I do

Hi, I am trying to save some base64 data to file, but somehow I can’t get it to work. Everytime I am trying to access external storage (/storage/emulated/0), I get Permission denied from createFile() or writeFile()—I have tried both already. I am also asking for permission beforehand, as you can see in my code snippet. I also added the stuff to AndroidManifest.xml.

The only location that doesn’t raise the Permission denied exception is RNFetchBlob.fs.dirs.DocumentDir, but that is /data/user/0/{bundleId}/files and I am not sure, what that’s translating to. This exact path does not exist on my phone, but I suspect it’s {Internal storage}/Android/data/{bundleId}/files. Even so, after running createFile()/writeFile() “successfully” there’s no file at that location.

Am I missing something crucial here? I’m really out of my depth on this one. I hope someone can help me.

• the version of installed library and RN project. react-native: v0.63.3 rn-fetch-blob: v0.12.0 Android 10 (Samsung Galaxy S10; One UI v2.5)

• a sample code snippet/repository is very helpful to spotting the problem.

const permissions = await Permissions.requestMultiple([
  Permissions.PERMISSIONS.ANDROID.READ_EXTERNAL_STORAGE,
  Permissions.PERMISSIONS.ANDROID.WRITE_EXTERNAL_STORAGE,
]);
console.log("permissions:", permissions);
if (
  permissions[Permissions.PERMISSIONS.ANDROID.WRITE_EXTERNAL_STORAGE] ===
    Permissions.RESULTS.GRANTED &&
  permissions[Permissions.PERMISSIONS.ANDROID.READ_EXTERNAL_STORAGE] ===
    Permissions.RESULTS.GRANTED
) {
  try {
    // const createdFilePath = await RNFetchBlob.fs.createFile(path, base64Data, 'base64');
    const createdFilePath = await RNFetchBlob.fs.createFile(
      `${RNFetchBlob.fs.dirs.DownloadDir}/test.txt`,
      "Hello World",
      "utf8"
    );
    if (createdFilePath) {
      console.log("created file path:", createdFilePath);
      return true;
    }

    console.warn("saveToFile() :: File was not successfully saved to dir.");
    return false;
  } catch (e) {
    console.warn(
      "saveToFile() :: RNFetchBlob.fs.createFile raised an exception:",
      e.message
    );
    return false;
  }
} else {
  console.warn("Permission to write to external storage not granted.");
}

If you need any additional info, just let me know.