Specific template cannot be edited on live server - 403 forbidden

[Neo]

I have a site that I just moved to a live server and it basically works.

I can edit all pages, add content and upload images with the superuser account, except for 1 page:

When I try to edit a hidden page (global-settings.php) that holds some global values that are used throughout the page,

and I want to save the changes, I am redirected to a 403 - forbidden page:

"Forbidden

You don't have permission to access /processwire/page/edit/ on this server"

On localhost I had no problems to edit the page, so I don't assume this a role permission problem as I am using the superuser-account.

Any idea what could be wrong?

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EDIT:

I have no idea why this was posted twice...

[Pete]

Is it a PW page and you're typing code into a textarea in the admin and saving it or something like that?

If it is then it will likely be some mod_security settings on your server that don't allow things that look like code to be sent via forms. Sometimes even individual words can trigger that - "Select", "Drop" etc - since to mod_sec they look like someone trying to do some damage.

[Neo]

Thanks for your quick response.

It is a normal PW page that is hidden, which holds a series of text fields for telephone, email, social media accounts etc. 

However, there is one field (textarea), which holds the google analytics tracking code of the page (<script> ... </script>),

which triggered the alarm. Moving the script part out of the variable and just using the tracking ID solved the problem.

Thanks