503 error when posting file to php server using formdata module using Node js and axios

Question

I'm trying to send a file from my Node js application to a PHP server hosting an opencart application. I'm using formdata and axios modules to make requests and upload files.

My problem is that I get this error Error: Request failed with status code 503

How to solve?

This is my code in Node.js:

let form = new FormData();
form.append("file", fs.createReadStream(path.resolve(zipFilePath)), path.basename(zipFilePath));

            try {
                let response = await axios.post(endpoint, form, {
                    headers: {
                        ...form.getHeaders(),
                    },
                });

                const result = response.data;
                if (result && result.status === "success") {
                    fs.unlinkSync(zipFilePath);
                }
            } catch (e) {
                console.log(e.toString());
            }

and php code (function in controller):

public function upload() {
        header('Access-Control-Allow-Origin: *');
        
        if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {
            $this->response->setOutput(json_encode([]));
        } else {
            // process the file posted
        }
    }

Answer 1

problem solved.

The problem is that the opencart application is set to maintenance mode on the backend, but the frontend is still working normally, so it was not noticed before.