Support » Plugin: WP Mail SMTP by WPForms » Fatal error saving Gmail settings

  • Resolved Marcoevich



    Upon saving the settings for Gmail, after filling in the Client ID and Client Secret, I get a fatal error and all settings disappear. Removing and reinstalling the plugin does not restore access. This is how my settings screen looks right now:

    This makes that I am completely unable to use the plugin now. Help?

    The error is this:

    Fatal error: Uncaught Error: Call to undefined function GuzzleHttp\choose_handler() in /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/guzzlehttp/guzzle/src/HandlerStack.php:42 Stack trace: #0 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/guzzlehttp/guzzle/src/Client.php(65): GuzzleHttp\HandlerStack::create() #1 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/google/apiclient/src/Google/Client.php(1125): GuzzleHttp\Client->__construct(Array) #2 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/google/apiclient/src/Google/Client.php(1087): Google_Client->createDefaultHttpClient() #3 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/google/apiclient/src/Google/Client.php(360): Google_Client->getHttpClient() #4 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/google/apiclient/src/Google/Client.php(835): Google_Client->authorize() #5 /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/google/apiclient/src/Goo in /home/doemee1q/zwijndrecht/wp-content/plugins/wp-mail-smtp/vendor/guzzlehttp/guzzle/src/HandlerStack.php on line 42

    The page I need help with: [log in to see the link]

Viewing 5 replies - 1 through 5 (of 5 total)
  • Hi @marcoevich,

    Thanks for reaching out. It looks like there is a conflict with the plugin or your theme due to the different versions of the GuzzleHttp library loaded one by WP Mail SMTP and another by one of your plugins or the theme. Please follow this troubleshooting guide to find out the conflicting plugin.

    I hope this helps!

    Hi @marcoevich – We haven’t heard from you in about a week, so I’m going to go ahead and mark this ticket resolved. If you still have questions, though, please feel welcome to continue the conversation.

    I am receiving the same Fatal error when I finish setting up the Gmail client api key and secret.

    Doing a search inside my wp-content directory for the file in question (HandlerStack.php) gives me these results:


    All these plugins are active except W3-Total-Cache.

    Thread Starter Marcoevich


    Just a heads up, this issue was never resolved for me. I just started to use a different plugin for one site.

    Hi @lwangaman,

    Thanks for providing the details. It is the conflict with one of those mentioned plugin, probably with wpdm-dropbox due to the different version of guzzlehttp being used. The fix for such conflicts will probably be included in the upcoming release.

    Have a good one!

Viewing 5 replies - 1 through 5 (of 5 total)
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