Support » Plugin: WP Mail SMTP by WPForms » Critical error (when plugin activated)

  • Resolved brupez


    Hello everyone! I already had the WP mail SMTP installed and configured but when I activated it show me this error everywhere and I can’t access anything…

    My site is up and running but I can’t change anything and proceed.

    This is the message:

    “There has been a critical error on your website. Please check your site admin email inbox for instructions.

    Learn more about debugging in WordPress.”

    Please anyone help me solving these, thank you!

Viewing 6 replies - 1 through 6 (of 6 total)
  • Same here… I wanted to configure WP Forms just now and add the SMTP plugin via WP forms dashboard.

    Complete site crash. Horrible to say the least. This should not happen. EVER.

    The quick fix for now is go to your FTP, Wp-content folder –> plugins –> remove wp-smtp folder completely. The site will then return to normal.

    They better fix this soon or I’m out.

    Plugin Author Gregor Capuder


    Hi @brupez and @xchristox,

    could you please enable WP debugging (WP_DEBUG and WP_DEBUG_LOG) on your WP site and report what the error message is saying? More info about WP debugging can be found here:

    After you post the error message here, we can help you investigate what the issue is and how to potentially resolve it.

    Take care!

    Thread Starter brupez


    @xchristox how do you go to your FTP? i need to install something?

    Plugin Author Gregor Capuder


    Hi @brupez,

    you should contact your web hosting support and they should be able to help you with FTP access or even disable the plugin for you.

    It would be super helpful if they could also check the PHP error logs and let us know what the error was. If there is nothing in the PHP error logs, they can enable the WP debugging mentioned above.

    Take care!

    Hi @capuderg!

    I have a more technical description for the error regarding this topic.

    The error occurs after updating to WordPress 5.5, the error occurs on line 13 within the class-smtp.php file in the wp-includes directory.

    require __DIR__ . '/PHPMailer/SMTP.php';

    It appears that the PHPMailer\PHPMailer\SMTP class (a dependency within your project) is required twice on the site (once in the class-smtp.php file and once within your plugin). This gives a fatal error on php witch results in a sitecrash.

    A temporary fix is to comment out line 13 within the class-smtp.php file within your wp-includes folder and temporary disable the plugin until a fix is released.

    Below I have some logs to share:

    Error log:

    PHP Fatal error:  Uncaught Error: Call to undefined function _deprecated_file() in /var/www/
    Stack trace:
    #0 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1197) : eval()'d code(84): require_once()
    #1 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1197): eval()
    #2 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1158): WP_CLI\Runner->load_wordpress()
    #3 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Bootstrap/LaunchRunner.php(23): WP_CLI\Runner->start()
    #4 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/bootstrap.php(74): WP_CLI\Bootstrap\LaunchRunner->process(Object(WP_CLI\Bootstrap\BootstrapState))
    #5 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/wp-cli.php(27): WP_CLI\bootstrap()
    #6 phar:///usr/local/bin/wp/php/boot-phar.php(11): include('phar:///usr/loc...')
    #7 /usr/local/bin/wp(4): include('phar:///usr/loc...')
    #8 {main}
      thrown in /var/www/ on line 6

    NGINX log:

    2020/09/02 15:28:24 [error] 32122#32122: *173790 FastCGI sent in stderr: "PHP message: PHP Fatal error: Cannot declare class PHPMailer\PHPMailer\SMTP, because the name is already in use in /var/www/ on line 30" while reading response header from upstream, client:, server:, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.3-fpm.sock:", host: "", referrer: ""

    Hope it helps! If you have any questions, feel free to contact me!


    • This reply was modified 7 months, 2 weeks ago by vrolyx.
    • This reply was modified 7 months, 2 weeks ago by vrolyx.
    • This reply was modified 7 months, 2 weeks ago by vrolyx.
    • This reply was modified 7 months, 2 weeks ago by vrolyx.
    Plugin Author Gregor Capuder


    Hi @vrolyx,

    our plugin does not require the SMTP class/file if it already exists. Usually, it’s required and initialized by WP core, but some plugins are doing it manually without checking for the class existence before doing so.

    Please check all your active plugins, themes and other custom codes on your WP site.

    This issue was experienced by others as well and was resolved by updating the plugin that caused the issue. Their PHP error was Fatal error: Cannot declare class PHPMailer \ PHPMailer \ SMTP, because the name is already in use in / on line 30 though. More info here:

    Your error does also looks strange: Call to undefined function _deprecated_file() The _deprecated_file is a WP core function and it’s really strange that it’s causing this error.

    Note: Editing WP core code is not a good idea.

    Take care!

Viewing 6 replies - 1 through 6 (of 6 total)
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