Page edit blank on admin

[icreation]

I have a bizarre error. One page (nothing unique about it) is blank in Admin.

The page works on the front end. - http://www.theroyalscottish.com/scottish-cruises-1/inner-clyde/ten-night-inner-clyde-cruises-1/

In admin we get a blank page when trying to edit. Other pages with the same template work fine.

I switched on debug mode in 'site' and 'wire' but the page is still blank. Page source is also blank.

Does anyone have any ideas?

[netcarver]

Anything in the error or exception logs, @icreation?

[icreation]

There are no recent entries in these logs at all.

[netcarver]

Ok, how about in the http server error log - not just PW's own log?

If you are running on a *nix based machine, the server error logs are often found in a subdirectory of /var/log/ (on my local machine, the logs are in /var/log/httpd/error-<sitename>.log.

If you are using php-fpm, you can check it's own logs too.

[icreation]

The only log we have on the server is when it is access in the browser. No errors are apparent, unless this is telling me of a 500 error?

Here is it:

<ip address> - - [20/Jun/2016:08:18:15 +0000] "GET /<admin-url-here>/page/edit/?id=1278 HTTP/1.1" 500 - "http://theroyalscottish.com/<admin-url-here>/page/" "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.84 Safari/537.36"

[adrian]

I get a 404 for that page on the front-end.

Quote

I switched on debug mode in 'site' and 'wire' but the page is still blank. Page source is also blank.

 

By the way, you shouldn't be editing anything inside wire - the config.php file in there contains all the defaults. Just change/add settings from it to site/config.php to make changes.

[Robin S]

If your host is running mod_security that might be the culprit. I've struck odd issues like this before that were resolved by disabling mod_security.

[icreation]

Thanks @adrian the page has been unpublished. But the front end of it was ok, showing no errors in debug mode.

We have just recreated the page and there are no issues. 

@Robin S - interesting about the mod_security but why would it affect only this page?

[kongondo]

@icreation I like to keep the names/URLs to my admin pages 'secret'...You probably want to edit your post above? 

[netcarver]

@kongondo - done, just in case.

[icreation]

Thanks

[Robin S]

8 hours ago, icreation said:

@Robin S - interesting about the mod_security but why would it affect only this page?

mod_security blocks processing based on regex rules: exactly what rules are implemented is up to the host or the person configuring the module. Perhaps your page contains a string that matches some overly-broad regex rule.

The intention behind mod_security is good but my experience has been that running the module results in many false-positives and the resulting problems are difficult to debug. On many hosts you can't even tell when mod_security has been triggered. My shared hosting enables it by default on every new account but I always disable it to avoid headaches.