A confirmed bug; I'll plan to investigate it late next month.

So the problem here, maybe, is that the + operator, when overloaded for array_merge(), will ignore values that share keys in the original array.  For example:

$array1 = array("foo");
$array2 = array("data");
$result = $array1 + $array2;print_r($result);

Output: Array ( [0] => foo )

Quick read over the array_merge() manpage wasn't very clear, in fact the manual appears to me to contradict this behavior entirely.  I'm on 5.2.4 fwiw, so maybe it's changed in 5.3 or something, although for the manual to reflect something from a release candidate/beta version or whatever it is, would be unfortunate.  Or the manual is just wrong.  Either one wouldn't surprise me.

I got to this point after reading the post linked above, checking those lines of code and finding that the result was not what it was apparently supposed to be.  Using array_merge() explicitly for those 3 assignments makes the 404 go away.  Since that looks like the original intent, I'll go with it for now.

defaults_rs.php, lines 275-279:

if ( ! empty($_GET['preview']) ) { $arr[$name]->usage->statuses->access_type['front'] = array_merge(array( 'draft', 'pending', 'future' ), $arr[$name]->usage->statuses->access_type['front']); $arr[$name]->reqd_caps['read']['post'] = array_merge(array ( 'draft' => array('edit_others_posts'), 'pending' => array('edit_others_posts'), 'future' => array('edit_others_posts') ), $arr[$name]->reqd_caps['read']['post']); $arr[$name]->reqd_caps['read']['page'] = array_merge(array ( 'draft' => array('edit_others_pages'), 'pending' => array('edit_others_pages'), 'future' => array('edit_others_pages') ), $arr[$name]->reqd_caps['read']['page']); }sorry about the formatting, if i put it in <pre> tags it blows up the page.

Sorry but that still doesn't work for me, I'm using Role Scoper Version: 1.0.4.1 on WP 2.8, any user without admin role can't preview his page while editing, it doesn't redirect on a 404 but only on the current version of the page, not the edited one.

Do you have WP_POST_REVISIONS defined in wp-config.php?

I do, and it prevents Page Preview from working once the revision limit is reached (whether admin or non-admin, and whether RS is activated or not). When I remove that definition, the Page Preview works fine.

I also have another page which has upwards of 100 revisions stored, and it won't preview regardless of WP_POST_REVISIONS definition or RS activation/non-activation. So I'm really suspecting a WP autosave/revisioning issue here.

I just checked and I don't have WP_POST_REVISIONS defined in wp-config.php.

I also just updated RS to 1.0.8 and WP to 2.8.4 and the problem is still there, I can't preview if I'm not admin

Kevin said:

Is this a private page? How many revisions do you have stored? Does the problem occur even for newly published pages?

It's the same on every page, they are all public, some have no revisions at all, some about ten or more, the problem occurs even for newly published page.

I don't know if it happens also during the creation of the page as my users don't have page creation rights, only edit rights.

Here is a screenshot of the capabilites of a generic user, I gave them on a page by page basis the "Page Author" Role in order for them to only see and edit their specific assigned page on the WP backend :

Everything works fine except for the preview.

Pending revisions are off, Caching is off

Thanks a lot for your help

The generic users are Subscriber, but I have one Contributor with the same credentials for testing purpose and it can't preview either.

I must admit that I don't know exactly what you are talking about, I customized the Page Author definition by clicking on "Options" in the "Roles" menu, and "RS Role Definitions" and checking/unchecking what I needed.

Next, a user subscribes, becomes a Subscriber by default, I then edit the page(s) he needs to have access, go down to "Authors" , select "Users" panel, and check the name, update the page and everything goes smoothly (except for the preview of course !), he is finally a WP Subscriber site wide, but a Page Author on his page(s).

Also I'd like to thank you again for your concern and very fast answers, I hope it'll eventually help other RS users with the same problem, though !