Why are files opening unstable?

Question

go

Why is one file opened and read, while the other is the same (located in the same folder) is not? The functions os.OpenFile("file.txt", os.O_RDWR, 0666) and ioutil.ReadFile("file.txt").
Is this a Go thing or are there nuances with the files themselves (attributes in Windows OS or something else)?
In the "Properties" of these files, everything is the same. In general, they are the same, created at the same time. OS Windows.

Answer 1

I suspect that os.OpenFile does not work, but ioutil.ReadFile does.
And most likely the matter is in the rights os.OpenFile("file.txt", os.O_RDWR, 0666).
Start by handling the error so that you can understand what exactly is wrong.

f, err := os.OpenFile("file.txt", os.O_RDWR, 0666)
if err != nil {
    log.Fatalln(err)
}

PS: ioutil.ReadFile("file.txt") calls the OpenFile(name, O_RDONLY, 0) function to open a file

Answer 2

Maybe OpenFile() is superfluous here, I added it in an attempt to solve the problem (it was the same without it).
The error for both functions is the same (the file was found correctly):