File.exists() returns false for file (directory) that actually exists

I am facing a weird issue (as so often happens) in my Android App.I will try to be as brief as i can.

First, i will show you the code and then provide some additional info. This is not the full code. Just the core of the issue.

Example code:

String myPath = "/storage/emulated/0/Documents";
File directory= new File(myPath);
if (!directory.exists() && !directory.mkdirs()) {
   throw new IllegalArgumentException("Could not create the specified directory: " + directory.getAbsolutePath() + ".");
}

Most of the time this works fine. A few times however the exception is thrown which means that the directory did not exist and could not be created. Out of every 100 runs, it works fine on 95-96 times and fails 4-5 times.

• I have declared the permissions for storage/read external storage/write external storage in my manifest and asked for the permissions on runtime. The problem does not lie there. (If anything i have too many permissions at this point :D ). After all, if it was a permission issue it would fail every time but in my case it fails at a rate of 4% or 5%.
• With the above code i am attempting to create a file that points to the 'Documents' folder. In my app i am really using String myPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS).getPath();
  In the specific device where the error occurs this path happens to be "/storage/emulated/0/Documents" and this is why i hardcoded it in the example code i gave you.
• If i use a file explorer app on the device i can see that the folder does exist and has some contents and also confirm that the path really is "/storage/emulated/0/Documents".
• This has never happened to me locally. Only the users of the app experience the issue and i know the issue exists thanks to Firebase/Crashlytics. The users have the exact same tablet as the one i am using for development, namely a Lenovo TB-8504X. (I work for a company and we provide both the software and the hardware).

So, do you have any thoughts on why this issue occurs?

Has someone ever experienced something similar?

Could the path to the 'Documents' folder sometimes be "/storage/emulated/0/Documents" and sometimes become something else on the same physical device?

I am an experienced Android developer but i am quite novice in Android architecture and the Android filesystem. Could it be that on start-up (when device is powered on or after a reboot) the filesystem has not yet 'mounted' the 'disk' at the point when my code checks if the directory exists? Here i am using the terms 'mount' and 'disk' as loosely as possible. Also my app is actually a launcher/parental control app so it is the first thing that gets fired when device starts. I am almost conviced that this does not make sense at all but at this point i am trying to see the greater picture and explore solutions that transcend typical Android development.

I would really appreciate your help as this issue is starting to get on my nerves.

Looking forward to any helpful responses.

Thanks in advance.

EDIT (27/08/2019) :

I came across this Java Bug Report although it is pretty outdated. According to this, when operating on NFS-mounted volumes, java.io.File.exists ends up performing a stat(2). If the stat fails (which it may do for several reasons), then File.exists (mistakenly) assumes that the file being stat'ed does not exist. Could this be the source of my troubles?

EDIT (28/08/2019) :

Today i am able to add a bounty to this question in an attempt to draw some more attention. I would encourage you to read the question carefully, look through the comments disregarding the one that claims that this has to do with costumer support from Realm. Realm code is indeed the one using the unreliable method but what i want to know is why the method is unreliable. Whether or not Realm can work around this and use some other code instead, is beyond the scope of the question. I simply want to know if one can safely use File.exists() and if not, why?

Once again, thank you all in advance. It would be really important to me to get an answer even if it is overly technical and involves a deeper understanding of NFS file systems, Java, Android, Linux, or whatever!

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