In our Wiki (http://scratch-dach.info MediaWiki 1.25.1, PHP 5.3.29, MySQL 5.5.44-log) we have sporadic problems when saving edits. At irregular intervals the Browser tries to download the index.php-file instead of committing edits. It seems that larger pages are more likely to be affected by this problem.
Downloading the PHP source usually means that Apache is misconfigured and does not allow to execute scripts in that directory, however usually all php scripts (and expecially the index.php from the wiki) execute well on the server.
We are hosting many wikis with the same extensions/config but only in this such errors occurs. The only specific difference between the Wikis seems to be that our database is more than 1 GB large. In the Apache-Log there are no suspicious entrys.
After some tests, we found out that the error only appears with pages containing an email address or an external link like
However, as mentioned the error is sporadic, sometimes the page with the link saves, sometimes we get the php-Download error. The problem is that we only have a "hoster" package from our provider, Strato, so we have no direct access to the php and apache modules.
We have searched for a long time in the internet, but I found no description of such a problem...
Any help is well appreciated!
(This question is a followup from stackoverflow where we have been told to put the question rather here at server fault.)