RNFS.exists() returns True but RNFS.readFile fails with error: File doesn't exist

```
async _loadCustomData(fileName, fieldName) {
const filePath = RNFS.ExternalStorageDirectoryPath + '/Download/' + fileName;

if (await RNFS.exists(filePath)) {
console.log("custom data file for " + fieldName + " exists");
let customData = RNFS.readFile(filePath);
customData = JSON.parse(customData);

let newState = {};
newState[fieldName] = customData;
this.setState(newState);
} else {
console.log("No such file as ", fileName);
}
}
```

The if-condition evaluates to True and console.log displays that the file exists, but, I am unable to read the contents of the file.
customeData evaluates to an object like this {_45: 0, _65: 0, _55: null, _75: null}

So, to read this Object, I did this:
```
RNFS.readFile(filePath)
.then((contents) => {
console.log(contents);
customData = JSON.parse(contents);

let newState = {};
newState[fieldName] = customData;
this.setState(newState);
})
.catch((err) => {
console.log(err.message, err.code);
});
```

Now, I get the error: "ENOENT: no such file or directory, open '/storage/emulated/0/Download/chimp-list-additional.json' ENOENT"

I have tried the approach here https://github.com/itinance/react-native-fs/issues/471 but it doesn't work for me.

Please help!!