Plugin cant connect to SMTP after install WP 5.5

I think unfortunately you may have lumped our two posts together in the same response. My hosting provider is WPEngine. Although they assisted in providing logging for the issue the source has nothing to do with another plugin or theme. 100% the source of the issue is WP 5.5 running in the 7.4 PHP. WHen the plugin is installed and running in a WP environment that has those conditions it will spin to a timeout 502. All indications on the server point to a memory leak. The plugin and application utilize all available resources on the managed shared host. As such not only can WP Engine not provide any server tweaks to allow for the application to function but they will terminate the application and eventually request the plugin to be removed in order to prevent resource overloads on their shared managed environment.

Indicating a plugin conflict only bears fruit if in fact conflict is a possibility. To illustrate that fact We have a bare install of WordPress – https://testmail.wpengine.com/. There are no plugins activated on this install other than WP Mail SMTP. There are no themes installed other than 2020, 2019 and 2017 which are the default WP installs. WP Mail SMTP is presently set to use office 365 as a Other SMTP the SMTP host but others including MailGun and SendGrid are failing as well. The only one that seems to work is the Default or None setting. We do not have accounts for SendinBlue, Pepipost or SMTP.com to test but we have tested Amazon SES.

I am happy to submit a ticket and provide you direct admin access to this install so you can see the issues related to an essentially bare metal install of the plugin.

Thanks in advance

Hi @tihjawi and @ejbrewer,

@tihjawi your last reply from hosting support is stating that other plugins/processes on the server are generating these open files and not closing them and when WP core’s PHPMailer/SMTP class tries to open a file it fails since there are no more file descriptors available. I’m not sure how we can change our plugin, so that it would change server limits (available file descriptors) and prevent other plugins from leaving open files. This sounds like our plugin is out of scope to fix/catch these issues.

@ejbrewer I’m not sure how a memory leak could be a culprit here, since the issue are opened (unclosed) files. When I was using the test sites of WPEngine I got the same issue on PHP 7.3., so this is not a combination of WP 5.5 and PHP 7.4 It just might be, that the server limitations for your case were not exceeded on PHP 7.3.

You are probably using WPEngine shared hosting, right? So these resources are shared with all the clients on the server. So if you create a new WP site on the same server and only install our plguin, the WP core PHPMailer\SMTP class will still try to open the file and it will fail, since the limitation is still there across the shared server.

I’ll get in touch with WPEngine support and try to debug and investigate what can be done in order to resolve this issue. If there is something we can do inside our plugin, we’ll do it.

Take care!

My hosting is WPEngine as well.

How come the only plugin having issues after migrating to 5.5 is yours?

You can’t simply cross your arms and stand by like this is solved… It is not.

hi hi!

I am having a similar issue and I would LOVE for a simple update to be posted to fix this issue. I am not a developer and cutting and pasting code is not ideal for me. These are the moments I yearn for something like squarespace (but I wont go easily!). Please help or give really detailed instructions?

Thanks

my contact page wont send, my check out page doesn’t work, my conf. emails are going out! Thank yoouuuu

I too am experiencing this “502 error” problem on a WP Engine (WPE) server when doing any of a variety of actions (On front end: submitting a form; On back end: deleting a post, sending a test email, etc.).

Here’s what’s in our debug.log file:

[21-Aug-2020 14:18:27 UTC] PHP Warning: stream_select(): You MUST recompile PHP with a larger value of FD_SETSIZE.
It is set to 1024, but you have descriptors numbered at least as high as 1062.
–enable-fd-setsize=2048 is recommended, but you may want to set it
to equal the maximum number of open files supported by your system,
in order to avoid seeing this error again at a later date. in /nas/content/live/greenteam1/wp-includes/PHPMailer/SMTP.php on line 1169

Deactivating the “WP Mail SMTP” plugin resolves the problem.

This is a WP Engine problem as other smtp plugins fail there, too. I had lengthy support chats with them and they acknowledge that a solution must be found. I tested on a different hosting service and everything worked as expected. I also narrowed it down to the combination of 5.5 and WPEngine, PHP version is not an issue.

Hi @weblink,

thank you for sharing your findings with others.

I also did some testing on a WPEngine hosted WP sites. On one WP site this issue was not reproducible and the emails were sent successfully. On the other one (other WPEngine hosting account) it experienced this timeout issue. So it looks like it does not happen on all WPEngine hosting servers.

I performed a few email sending tests on this failing WP site:
– trying to send via Test Email,
– trying to send via direct PHPMailer class (v6.1.6 -> bundled with WP 5.5) inside the plugin code,
– trying to send via direct PHPMailer class (v6.1.6 -> bundled with WP 5.5) in early WP code execution (wp-config).

I’ve also updated the PHPMailer class in WP from 6.1.6 to 6.1.7 and it did not resolve the issue.

All these tests were also performed with the WP Mail SMTP plugin deactivated and all tests resulted in the same timeout and this error:

PHP Warning:  stream_select(): You MUST recompile PHP with a larger value of FD_SETSIZE.
It is set to 1024, but you have descriptors numbered at least as high as 1322.
 --enable-fd-setsize=2048 is recommended, but you may want to set it
to equal the maximum number of open files supported by your system,
in order to avoid seeing this error again at a later date. in /..../wp-includes/PHPMailer/SMTP.php on line 1169

And as @weblink said, this issue happens on other SMTP plugins as well.

It looks like WPEngine has some issues with PHPMailer class, that was updated with WP 5.5. Since the error is hosting/server related, I think it’s best that you contact your hosting (WPEngine or other) and show them this thread. I think they should test out PHPMailer v6.1.6 class, which is part of the WP core and once that is fixed our plugin should start working OK as well.

Please let us know if you have any updates regarding this issue, so others will also know what to do if a solution is presented by your hosting provider.

Thank you and have a nice day!

Hi Gregor (@capuderg),

Thanks for doing all this legwork. This does sound like a sneaky bug.

However, I would have to dispute one of your findings — at least on my client’s site (https://thegreenteam.org/) hosted on WP Engine. When I disable “WP Mail SMTP”, I can send a test email from the website (using the WP Email Template LITE plugin) without problem. When I re-activate “WP Mail SMTP” and try to send another test email, I get the “502 error” I reported earlier. So it appears to me that there’s still a correlation between the plugin and the problem.

If I can provide you any more information that would help, please let me know.

Thanks!
Larry

Hi Larry,

when you have WP Mail SMTP enabled, you are using the “Other SMTP” mailer where you configure the SMTP settings, so your WP site is using SMTP connection (PHPMailer class with SMTP connection).

When you disable the plugin you are using default PHP email sending functionality. So you are no longer using PHPMailer with SMTP connection. That’s why the emails start sending for you after you disable our plugin.

What I’ve done with my tests on PHPMailer class… I’ve configured the SMTP connection with the updated PHPMailer class in WP 5.5 and it has the same issue of timing out (even when our plugin is disabled).

Have a nice day!

Thanks for explaining that Gregor.