Warnings on dashboard: Notice: Trying to get property of non-object in wp-includes/capabilities.php

[grandslambert]

I just upgraded a local install to 3.1 and have the debug mode on. Now, on the dashboard the "Recent Comments" box is filled with notices. I will attach a screen-shot of the notices. Though this doesn't show when debug mode is off, I have to assume that something isn't working with all of these warnings.

[grandslambert]

Screenshot of warning notices in the Recent Comments box on the dashboard in 3.1

[grandslambert]

Another screen shot of the comments page filled with warnings.

[ocean90]

Do you have deactivated all your plugins?

[scribu]

Those notices are most likely caused by a plugin doing something wrong.

Put the following gist in your mu-plugins folder to see a backtrace. ​https://gist.github.com/625769

[grandslambert]

OK, I did a clean install of 3.1 and turned on debug mode and it does not happen. Went back to other install and removed all plugins, still happens. Then I noticed there were some comments for posts that were no longer on the site. Once I deleted those from the database the errors went away. Apparently another bug which I may not be able to track prevented these comments from deleting when the posts were deleted. I will look into that, but perhaps a check to make sure a comment is associated with a post could prevent these errors -though it is not likely to happen all that often.

[ocean90]

grandslambert, would be nice if you can add the backtrace (see scribu's comment) to investigate it.

[grandslambert]

How would that help me if there are no errors showing now? The problem was bad data, likely caused by a bad plugin, and certainly not something that should be the concern of WordPress core developers. I doubt very much that any other user is going to encounter this problem.

[ocean90]

Okay, thanks.

[frumph]

Screenshots of notices in the exact place as above, but with ver 3.4

[frumph]

Reopening this ticket, I'm having the same situation.

Twentyeleven, no plugins activated.

Although I had a plugin enabled that created a custom post type, that has comments on their custom post type posts.

More Info: I had attempted to import the "theme unit test" which had issues and failures importing, couldn't retrieve images etc.

[frumph]

notices in the comments section of the wp-admin

[nacin]

Okay, based on the description, this should be reproducible back to 3.0.

So the issue is two-fold:

1. What to do about comments on a post of a non-existent type? and
2. map_meta_cap() needs to be a bit more resilient here.

[frumph]

Is it possible to do a check under the call for get_post_type_object, since it returns null we can gather that it must have existed at some point in time and then refer to using say 'post' as a fallback for the meta_cap ? -- probably could be done cleaner in the function get_post_type_object()

if (is_null($post_type_object)) $post_type_object = get_post_type_object( 'post' );

[scribu]

I don't think we should default to 'post' if the CPT is null.

IMO, the cap check should fail, unless the user has 'moderate_comments'.

[SergeyBiryukov]

Related: ticket:19590:12

[johnjamesjacoby]

Related: #21031

[nacin]

Duplicate of #19590.