Did you actually experience this error or is it reported by some static analysis tool?

My colleague experienced it:

[2024-10-24T09:40:12.921200+00:00] local.ERROR: Trying to access array offset on value of type null {"userId":1,"exception":"[object] (ErrorException(code: 0): Trying to access array offset on value of type null at C:\\laragon\\www\\project\\vendor\\symfony\\mailer\\Transport\\Smtp\\Stream\\AbstractStream.php:91)
[stacktrace]

Which exact version of the Mailer component do they have installed?

Yes, to replicate you can test with these details (invalid username/password).

SMTP host: smtp.mailtrap.io
Port: 587
Encryption: STARTTLS
Username: a
Password: a

This is on v6.4.12 of symfony/mailer

That is strange. I think we should investigate why there's no warning from PHP. To me, false should be returned only when there's an error. Looks like that's not always the case, but then, what happened? We need to provide the best error message we can. Can we do better than an empty string? That's what I'm wondering.

According to the documentation false is also returned when no more data can be read:

If there is no more data to read in the file pointer, then false is returned.

But I wonder how that could happen here as the method should have returned already earlier then because of the feof() at its beginning, right.

Closing. Cannot replicate 🤷🏼

@bytestream and @nicolas-grekas, I just ran into this error myself, but in the vendor/symfony/mime/Part/TextPart.php file. Specifically in getBody(). If body is a file it calls @file_get_contents($this->body->getPath()). In my case, the path is a URL and returned false because the URL returned a 400 error. No error is surfaced from error_get_last but if I remove the @ an ErrorException is thrown from file_get_contents

ErrorException: file_get_contents(https://url-that-returns-a-400-response): Failed to open stream: HTTP request failed! HTTP/1.1 400 Bad Request

Obviously I should not be providing a 400 url, but the InvalidArgumentException never gets thrown, because the code is trying to pull the message off of null from error_get_last.

@skylerkatz On which exact version of the Mailer component do you experience the issue? Could this be fixed by #59404?

I am on v7.2.3 of the mailer and v7.2.4 of symfony/mime.

@skylerkatz I tried to reproduce your issue, but I was not able to do so. My last guess is that you maybe have a custom error handler that influence the result of error_get_last(). Otherwise, please create an example application that allows to reproduce it and open a new issue to keep track of it.