I'm using Symfony 6.3 with PHP 8.2 on macOS and trying to upload a file using Symfony's HTTP client:

$file = fopen('/path/to/image.jpg', 'r');
$this->client->request('POST', '/image/processing/endpoint', [
    'body' => [
        'image_file' => $file,
    ],
]);

However, running this code is causing a TransportException with the message:

Uploaded stream ended for body part "image_file".

The exception in question is being raised in line 384 of Symfony\Component\HttpClient\HttpClientTrait as follows:

if (feof($v)) {
    throw new TransportException(sprintf('Uploaded stream ended for body part "%s".', $k));
}

It seems like the end-of-file test is returning true for some reason, however if I add the following line directly before I create the request in the code above, it is outputting bool(false):

$file = fopen('/path/to/image.jpg', 'r');
var_dump(feof($file));
// snip

Any other checks for file validity (such as file_exists and is_readable on the path) are confirming that the file path is definitely correct!

I am well and truly stumped, and wondered if anyone here could give me any advice on how to overcome this issue please?