上传后移动图像不能使用PHP代码

Question

我的代码存在问题。我不知道我的代码有什么问题，因为当我测试并运行它到PHP版本5.4时，这是有效的。

然后，在我使用PHP版本5.6传输文件之后，这不再适用了。

请帮忙。我是新来的。

以下是从表单上传图片的代码

if(!empty($_FILES["cover"]["name"])){

        $ext = explode(".",$_FILES["cover"]["name"]);
        $filename = substr(md5(rand(5,1000).$_FILES["cover"]["name"]),5,15).'.'.$ext[1];
        $uploadOk = 1;
        $imageFileType = pathinfo($filename,PATHINFO_EXTENSION);

        // Check file size
        if ($_FILES["cover"]["size"] > 2621440 /*2.5mb*/) {
            echo "<script>alert('Sorry, your file is too large. Be sure to optimize the image you want to upload.');</script>";
            echo '<meta http-equiv="refresh" content="0; url='.$BASE_URL.'new.php?error=file"/>';
            $uploadOk = 0;
        }


        // Allow certain file formats
        if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
        && $imageFileType != "gif" ) {
            echo "<script>alert('Sorry, only JPG, JPEG, PNG & GIF files are allowed.');</script>";
            echo '<meta http-equiv="refresh" content="0; url='.$BASE_URL.'new.php?error=file"/>';
            $uploadOk = 0;
        }
        // Check if $uploadOk is set to 0 by an error
        if ($uploadOk == 0) {
            echo "<script>alert('Sorry, your file was not uploaded.');</script>";
            echo '<meta http-equiv="refresh" content="0; url='.$BASE_URL.'new.php?error=file"/>';
        // if everything is ok, try to upload file
        } else {
            if (move_uploaded_file($_FILES["cover"]["tmp_name"],"uploads/".$filename)) {
                echo '<meta http-equiv="refresh" content="0; url='.$BASE_URL.'edit.php?id='.$bookid.'"/>';
            } else {
                echo "<script>alert('Sorry, there was an error uploading your file.');</script>";
                echo '<meta http-equiv="refresh" content="0; url='.$BASE_URL.'new.php?error=file"/>';
            }
        }

    }

非常感谢任何建议和意见。感谢。