Title: Critical errors
Last modified: May 20, 2026

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# Critical errors

 *  [pwidner](https://wordpress.org/support/users/pwidner/)
 * (@pwidner)
 * [2 weeks, 4 days ago](https://wordpress.org/support/topic/critical-errors-35/)
 * We have recently started receiving critical errors related to this plugin.
 * Testing email from within the plugin doesn’t work and has critical error posted.
 * Even just logging into website creates a critical error.
 * Processing an order in woocommerce produces error.
 * We are not receiving emails from the website.
 * Here is a debug log file from test email which shows critical error. Any ideas
   on how we can resolve this?
 *     ```wp-block-code
       [20-May-2026 22:09:07 UTC] PHP Fatal error:  Uncaught Error: Call to undefined function GuzzleHttp\choose_handler() in /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/vendor/guzzlehttp/guzzle/src/HandlerStack.php:40Stack trace:#0 /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/vendor/guzzlehttp/guzzle/src/Client.php(65): GuzzleHttp\HandlerStack::create()#1 /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/src/Google/Client.php(1058): GuzzleHttp\Client->__construct(Array)#2 /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/src/Google/Client.php(1032): Google_Client->createDefaultHttpClient()#3 /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/src/Google/Client.php(277): Google_Client->getHttpClient()#4 /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/src/Google/Client.php(255): Google_Client->fetchAccessTokenWithRefreshToken('1//0fxe0LdJCpwC...')#5 /home/xxx/public_html/wp-content/plugins/gmail-smtp/class.phpmaileroauthgoogle.php(154): Google_Client->refreshToken('1//0fxe0LdJCpwC...')#6 /home/xxx/public_html/wp-includes/PHPMailer/SMTP.php(636): GmailXOAuth2->getOauth64()#7 /home/xxx/public_html/wp-content/plugins/gmail-smtp/class.phpmaileroauth.php(154): PHPMailer\PHPMailer\SMTP->authenticate('', '', 'XOAUTH2', Object(GmailXOAuth2))#8 /home/xxx/public_html/wp-includes/PHPMailer/PHPMailer.php(2175): PHPMailerOAuth->smtpConnect(Array)#9 /home/xxx/public_html/wp-includes/PHPMailer/PHPMailer.php(1798): PHPMailer\PHPMailer\PHPMailer->smtpSend('Date: Wed, 20 M...', 'test\r\n')#10 /home/xxx/public_html/wp-includes/PHPMailer/PHPMailer.php(1615): PHPMailer\PHPMailer\PHPMailer->postSend()#11 /home/xxx/public_html/wp-content/plugins/gmail-smtp/main.php(1128): PHPMailer\PHPMailer\PHPMailer->send()#12 /home/xxx/public_html/wp-includes/class-wp-hook.php(341): gmail_smtp_pre_wp_mail(NULL, Array)#13 /home/xxx/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters(NULL, Array)#14 /home/xxx/public_html/wp-includes/pluggable.php(231): apply_filters('pre_wp_mail', NULL, Array)#15 /home/xxx/public_html/wp-content/plugins/gmail-smtp/main.php(229): wp_mail('patrick@marketi...', 'test', 'test')#16 /home/xxx/public_html/wp-content/plugins/gmail-smtp/main.php(158): GMAIL_SMTP->test_email_settings()#17 /home/xxx/public_html/wp-includes/class-wp-hook.php(341): GMAIL_SMTP->options_page('')#18 /home/xxx/public_html/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters('', Array)#19 /home/xxx/public_html/wp-includes/plugin.php(522): WP_Hook->do_action(Array)#20 /home/xxx/public_html/wp-admin/admin.php(264): do_action('settings_page_g...')#21 /home/xxx/public_html/wp-admin/options-general.php(10): require_once('/home/xxx/p...')#22 {main}  thrown in /home/xxx/public_html/wp-content/plugins/gmail-smtp/google-api-php-client/vendor/guzzlehttp/guzzle/src/HandlerStack.php on line 40
       ```
   

Viewing 1 replies (of 1 total)

 *  Plugin Author [Noor Alam](https://wordpress.org/support/users/naa986/)
 * (@naa986)
 * [2 weeks ago](https://wordpress.org/support/topic/critical-errors-35/#post-18917684)
 * Hi, This is similar to these issues:
 * [https://wordpress.org/support/topic/guzzle-fatal-error-2/](https://wordpress.org/support/topic/guzzle-fatal-error-2/)
 * [https://wordpress.org/support/topic/guzzlehttp-issue/](https://wordpress.org/support/topic/guzzlehttp-issue/)

Viewing 1 replies (of 1 total)

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 * 1 reply
 * 2 participants
 * Last reply from: [Noor Alam](https://wordpress.org/support/users/naa986/)
 * Last activity: [2 weeks ago](https://wordpress.org/support/topic/critical-errors-35/#post-18917684)
 * Status: not resolved