Hi ! I finally managed to finish my mobile game and install it on my phone. The save system works perfectly :). However, I wanted to test on my brother’s phone and the save won’t create. Does anyone have any idea why this is happening please? I specify that I tried with the option “use external file dir” checked and unchecked but neither of the two works and that my brother authorizes the application to access his storage. My target sdk is 30. thanks in advance
So many un-answered questions in your question!
Which particular phone models are you using, which versions of the OS are you using, which carriers are you using, how much free space is there, when it “doesn’t work,” what actual errors are you getting in the logs, …
hi thanks for your answer. My phone (where the save works) runs on android 10 and my brother’s phone (where the save does not work) runs on android 13. I learned in the meantime that the security concerning the storage of the applications had been updated. day on android 11. I think it comes from there but then I don’t know how to fix it.
it can’t come from storage space because my brother’s phone has 30gb free and can you tell me how i see the logs on my phone please?
To see logs on phone, you attach with a debugger/IDE and use the LogCat viewer.
Either use adb shell logcat from the command line or install Android Studio and Attach to the phone and use the LogCat tab.
The nice thing about this is that it works for any phone with development enabled, no particular other program or install needed. Just connect and look at logs. (You will see that everything on your phone is spewing logs all the time… it’s quite nosy in there!)
Also, if it’s a v10 vs v13 difference, chances are there’s some new Storage permission requirement you need to set up the game to ask for in the Manifest.
There’s a ton of them you can ask for, but you should only ask for the ones you really need:
ok thank you very much i understand better how to see the logs than my phone. I’ll do my best to make it happen and I’ll let you know 
I managed to get the logs but I don’t understand anything can you help me please
You’re going to have to read some tutorials on how to debug Android applications and how to use Logcat – that’s a bigger topic than a simple forum thread can answer.
In brief, you’ll want to largely look for log messages from your particular application (you can scroll through all logs for a bit, looking for the tags that come from your app, to familiarize yourself.)
Then you can use matching/searching/filtering to find the area in question. You’ll frequently want to make sure you add logging in your own app when starting the operation in question. The “Print to Screen” Blueprint node can actually also print to log, this is helpful.
In general, though, being able to wade through tons of log files to figure out where your own data is, is a skill that any strong developer will need to develop, and it takes practice.
Hopefully this is not “bad news,” but instead “a new opportunity!” 
Ok I see thank you I just have to look on the internet for tutorials. thank you very much and it’s not a bad news for me😁