I try to install Craft 3 but I encounter an issue at the very beginning. I uploaded the CMS via FTP and completed manually the .env file. When I try to run the installation, I get stuck at the account creation (the second step…) I want to create my account but the next button is doing nothing. I get an error 400 "Bad Request // Unable to verify your data submission." When I send the form to create the admin account (POST to http://mywebsite.com/web/index.php?p=admin/actions/install/validate-account).

The server meet the requirements of Craft CMS (runned the server check and was ok). The DB connection is fine.

I tried to delete and reupload all the CMS but nothing changed.

Therefore, I'm unable to install Craft :| I saw some topics of the same issue but they're all unanswered.

Thanks a lot !

Here are the corresponding logs :

            2018-04-13 06:05:42 [2a02:a03f:3c1f:a00:6826:543f:275d:d8d5][-][-][error][yii\web\HttpException:400] yii\web\BadRequestHttpException: Unable to verify your data submission. in /home/MyWebsite/www/vendor/yiisoft/yii2/web/Controller.php:166
            Stack trace:
            #0 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Controller.php(53): yii\web\Controller->beforeAction(Object(yii\base\InlineAction))
            #1 /home/MyWebsite/www/vendor/yiisoft/yii2/base/Controller.php(155): craft\web\Controller->beforeAction(Object(yii\base\InlineAction))
            #2 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Controller.php(74): yii\base\Controller->runAction('validate-accoun...', Array)
            #3 /home/MyWebsite/www/vendor/yiisoft/yii2/base/Module.php(528): craft\web\Controller->runAction('validate-accoun...', Array)
            #4 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Application.php(238): yii\base\Module->runAction('install/validat...', Array)
            #5 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Application.php(446): craft\web\Application->runAction('install/validat...', Array)
            #6 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Application.php(410): craft\web\Application->_processActionRequest(Object(craft\web\Request))
            #7 /home/MyWebsite/www/vendor/craftcms/cms/src/web/Application.php(147): craft\web\Application->_processInstallRequest(Object(craft\web\Request))
            #8 /home/MyWebsite/www/vendor/yiisoft/yii2/base/Application.php(386): craft\web\Application->handleRequest(Object(craft\web\Request))
            #9 /home/MyWebsite/www/web/index.php(21): yii\base\Application->run()
            #10 {main}
  • Can you find the 400 Bad Request entry in your craft/storage/logs folder and share the full stack trace leading up to it?
    – Brad Bell
    Apr 12, 2018 at 5:19
  • Hi Brad and thank you for your answer, I edited my post to add the logs !
    – Holino
    Apr 13, 2018 at 13:15
  • Have seen that happen when you try to install over http and the site is configured to use https (and visa-versa). And if you're using Chrome it can be overly aggressive with it's caching if you make a switch (even in incognito mode). Have had to clear all of Chrome's caches before it would change sometimes.
    – Brad Bell
    Apr 14, 2018 at 23:40

1 Answer 1


Hello and thanks Brad !

I was actually using Firefox. When I tried to install Craft 3 via Chrome (which has never gone to the website before) the issue was solved and I could access to the next page. Should be a cache issue !

Thank you !


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