This is a comment on Requested URL was not found on this server, posted by WikiAdmin at 03.11.2014 19:26

View source for This is a valid bug

I could reproduce the case within the admin panel (admin/modules/configsystem.php) and I also found the cause

in admin.php
// enable rewrite_mode to avoid href() appends '?page='
if ($engine->config['rewrite_mode'] == false)
	$engine->config['rewrite_mode'] = 1;

I'll fix this soon.