Sometimes when you publish a new menu item, and everything seems to be OK, when you try to access the new menu item you just created you hit the wall: instead of the intended content you'll see the following error:
Even more confusing can be the situation when a link which used to work behaves this way. The target content item is published, access rights are set to Public, and you still got this message! What can be wrong here?
The causes can be more, than you may imagine. The most usual cause of this is that you (or anther Administrator) has unpublished the category or section where the content item belongs to. Check this first, in 90% of cases this is the cause.
So, check all your permissions! I mean ALL of them! You must have all of the following published, permissions set to public,
Additionally the publication start and end date must to be correct, the item also need to be published now. The "Start Publishing:" date and time must be before the current date and time of your server and the "Finish Publishing:" date and time must be after the current date and time of your server. To be sure, and you have problems with a newly created content item try to set the Start Publishing date with a day before. This usually fixes the problems related with server time.
But here are some more possible causes and accompanying quick fixes:
The problem also can be related to menuing:
Other known occurrences of problem (we suggest to search in the most appropriate locations, as Joomla Forums, the components support forums for cure):
If none of above helps, then the problem it's more serious, as described in the following posts:
This is caused by the well known fact that in very rare occasions Joomla generates wrong Itemid's for content elements. If this is the case, you need help from a Joomla guru, definitively!