When I click on the page history button, I get the following warnings:

PHP Warnings
lib/main.php:656: Notice[1024]: PageHistory: Cannot find action page
lib/main.php:576: Notice[1024]: PageHistory: Unknown action

When I search google for this, I get a lot of pages from online wiki's with the same problem. Anyone know how to handle this problem, what causes it? I'm not really an experienced php/mysql programmer.

This also happens with the history button etc. Searching this forum I can't find a solution.

Btw, some more useful info... The wiki is running on Apache/2.0.48 (Fedora) on Redhat Linux. The wiki is version 1.3.10.

Cool! :-) For some reason it already worked. I changed the config file (SERVER_NAME = wiki.mydomain.com) for the subdomain name, but that didn't help, in fact made things worse as this only changed the links which didn't work anymore. Then, setting it back to the default, it seemed to work!

But just when I wanted to post this, I saw your comment, and tried that as well. Thanks!

You need to create a page with the plugin invocation.
(an "action page")

for PageHistory you need the page "PageHistory"
with the line
<?plugin PageHistory" ?>

On recent versions you can add ?action=upgrade to your url, and all required action pages will be loaded automatically.