What could be causing the error message "Dateityp ist NICHT zugelassen" despite all files being of type "audio/mpeg"?

The error message "Dateityp ist NICHT zugelassen" translates to "File type is NOT allowed" in English. This error could be caused by incorrect file type checking in the code. To solve this issue, ensure that the file type validation is correctly checking for "audio/mpeg" type files.

// Check if the uploaded file is of type "audio/mpeg"
if ($_FILES['file']['type'] != 'audio/mpeg') {
    // File type is not allowed
    echo 'Dateityp ist NICHT zugelassen';
} else {
    // File type is allowed, proceed with file processing
    // Your code to handle the file upload and processing goes here
}