server error when saving the page

Does saving the page work when the plugin is disabled? To which file did you add the code?

Saving the page when the plugin is disabled works fine.

I added the code to the file that has the head info (header.php)

Which file exactly, what theme are you using? Do you get the internal server error on the website itself or on the WP Dashboard?

this happens in various themes from kriesi.at

i get the error when pressing ‘publish’ on the pages.
happens on all pages, where trying to add the code

An internal server error can be caused by several things.
Please see this article on WPBeginner to see if any of the solutions solves your problem.

The most important things are:

• Checking the .htaccess file
• Increasing the php memory limit

nop that is not it…

What happens when you use the default WordPress theme (TwentyTwelve) and do not insert the action hook into it?
So:

1. Activate the default theme
2. Activate my Google Content Experiments plugin
3. Create or edit a WordPress page
4. Tick the box to activate the experiment on that page
5. Insert the Google Experiment code into the box
6. Save the page

Do you still get an internal server error in this case?

I am having the same problem. Running 3.5.2.

Everything works fine right up until the moment i hit ‘publish’. Page publishes fine as long as i don’t fill in the experiment code box.

I am running a custom theme… added code to head….

I just noticed that the post will publish fine on my local mirror of the website.. but not on the live version.

Unfortunately I don’t have any idea why you are having problems.
I just tested the latest version of the plugin on WP 3.5.2 with and did not encounter any problems.