Se puede abrir pero no se puede leer el archivo

I am trying to open a file using file = fopen("filename.txt") and read that file character by character using fgetc(file).

Opening the file is successful, but fgetc() always returns -1. To find the error I tried to use ferror(), which was true after using fgetc. But that still doesn't give any information on why the error occurs. So I was trying to use strerror(errno) to obtain details about the occurring error, but this returns "No Error". Does anyone have any idea what the error could be?

Aquí está la parte relevante del código:

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

FILE* file1;
int c;

....
void main(void) {
    file1 = fopen("C:\\Users\\student\\text1.txt", "r");
    if (NULL == file1) {
        send_string("Error opening file!"); 
    } else {
        send_string("File opened successfully\n");
        c = fgetc(file1);
        if (feof(file1))
            send_string("End of file reached"); 
        else if (ferror(file1))
            send_string("Error in file!");
        send_string(strerror(errno));   //output is "No Error!"
    }
}

El resultado es:

"Error in file!"
"No Error!"

The file I am trying to open is a simple text file containing some lines of random characters. I also tried to open a .csv file with the same result.