Hi, I have been having this issue intermittently with Cornerstone, I create new content and cannot save the page. The green progress bar gets 95% of the way across the top of the page, I get the confirmation message, but the progress bar freezes and the page does not save. I can save the blank page, but not having added content. I have disabled all caches and all add-ins except cornerstone, with no luck. Everything is up to date.
Hi there,
Thanks for writing in.
Maybe the request is being blocked due to the content you’re adding. It’s possible that it contains iframe, special characters, or some element that is not allowed by your hosting. Would you mind providing your admin login credentials in a secure note? And please provide the content you’re adding, maybe I could find something 
Thanks!
This morning I noticed that there was a Cornerstone update to 2.1.0, my site was running 2.0.6 and not offering any update (until today). I have installed it and I was being given the “A conflict on the front end of your site has prevented the preview from loading.” error.
I have disabled ALL plug-ins except for cornerstone, this error seems to have been generated by the Polylang Pro plugin, which is up to date. I disabled this plugin and was able to preview and save the template without any problems.
I’ll try and get in touch with the developers of that plugin.
I am having this same issue. We have even uninstalled and reinstalled all plugins and the page still won’t save. It’s also loading extremely slow. All I want to do is add a link to a button.
@Osztreicher - Thank you
Please try improving your memory limite, if that does not work, open a new thread briefly explain your situation and provide your credentials in a secure note.
To Improve your memory limit Would mind adding this in your wp-config.php located at the root directory of your site.
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
You can add it before the line
/* That’s all, stop editing! Happy blogging. */
Here you have a video tutorial in any case:
Let us know how it goes.
Thanks