Hi ddiazher, I suggest you to post this question on the plugins support page. So they debug and gives a better solution with a minimal time.
Here is a Contact Form 7 Support link: https://ww.wp.xz.cn/support/plugin/contact-form-7
Thanks,
Sami
Seems the error is coming from Cornerstone (and it’s Contact Form 7 integration), not Contact Form 7 itself.
Access your server via SFTP or FTP, or a file manager in your hosting account’s control panel, navigate to /wp-content/plugins/ and delete the entire /cornerstone/ directory there.
You’ll be able to use your site after, but before reinstalling the plugin, I recommend reporting the issue at https://ww.wp.xz.cn/support/plugin/cornerstone so the plugin’s developers and support community can help you with this.
In the meantime, you can probably remove the error and get back into your site by using your FTP client or the file manager in your hosts control panel to rename or remove the “cornerstone” plugin. The cornerstone plugin is the source of the conflict/error message you’re seeing.
