Feed <lastBuildDate> Bug

[onlanka]

My wordpress site's feed doesn't show latest post's date and time in the

<lastBuildDate>

Eg:

<lastBuildDate>Wed, 15 May 2019 10:42:52 +0000</lastBuildDate>

<pubDate>Fri, 17 May 2019 08:43:44 +0000</pubDate>

There is a gap of 2 days between latest post and Last Build Date!

I don't use any cache plugin.
PHP Version: 7.3

Please explain me how to fix this issue.

My website's feed URL:

https://www.onlanka.com/feed

[onlanka]

I got confirmed, this is a database issue.
Wordpress sites older than 7-8 years could be affected.

Here what I did to get confirm the place of issue:

1. I duplicated wordpress site into a subfolder (database also duplicated to seperate from main site)

New Test location: https://www.onlanka.com/wptest/

2. Deactivated all the plugins.
3. Deleted all the plugins.
4. Activated wordpress default theme twentynineteen
5. Then posted a new test post.
6. Then checked https://www.onlanka.com/wptest/feed

7. Still <lastBuildDate> not updating with latest posts.
8. Also When I visit feed link https://www.onlanka.com/wptest/feed , it gives the file as feed but I checked another fresh installation of wordpress and it gives xcGddgR random letters as feed file name.

9. Then I did wordpress fresh installation + fresh database and then did test post. It has no issues, Then I replaced database with my old database, They issue came as said above.

If you have a way to repair feed updating part in the database, this could be fixed.

Please give me a solution for this.

[SergeyBiryukov]

Hi @onlanka, welcome to WordPress Trac! Thanks for the report.

Does the issue still happen with all plugins disabled and a default theme (Twenty Nineteen) activated?

Moving to 5.2.2 for visibility, could be introduced in [44948] / [45247].

[onlanka]

@SergeyBiryukov Yes, I disabled all the plugins, also activated default theme twentynineteen.

But it is still happening

My blog is older than 8 years, but I did regular updates in timely manner. only older WordPress installations affected.

Please release a patch to repair feed

[onlanka]

Finally I fixed it, But this might be Not the correct way.
But I had to do this until official patch released for this issue.

What I did is, in wp-includes/feed-rss2.php

Code line 45 was:

<lastBuildDate><?php echo get_feed_build_date( 'r' ); ?></lastBuildDate>

I replaced it with:

<lastBuildDate><?php echo mysql2date( 'D, d M Y H:i:s +0000', get_post_time( 'Y-m-d H:i:s', true ), false ); ?></lastBuildDate>

This has fixed the problem, but again this might not the correct way to fix this problem!

I applied this fix to my live blog, it's feed URL is:

https://www.onlanka.com/feed

[Rarst]

Yeah, it's a bug in new function since it relies on string sort in max() after it applies arbitrary date format (so result is not all necessarily string sortable). Adding patch.

[mukesh27]

Patch.

[mukesh27]

@Rarst added fix patch. i have not updated page so i can't get update and added patch.

[SergeyBiryukov]

Looks good to me.

[desrosj]

In 45367:

Feeds: Ensure a feed’s <lastBuildDate> has the correct date.

The maximum modified time for a is currently being determined after an arbitrary date format is applied. Because the string sort in max() is being used to return the highest (most recent) modified value, the incorrect date is sometimes returned. This was introduced in [45247].

Props onlanka, Rarsr, mukesh27.
Fixes #47304.

[desrosj]

Reopening to backport.

[desrosj]

In 45368:

Feeds: Ensure a feed’s <lastBuildDate> has the correct date.

The maximum modified time for a is currently being determined after an arbitrary date format is applied. Because the string sort in max() is being used to return the highest (most recent) modified value, the incorrect date is sometimes returned. This was introduced in [45247].

Merges [45367] to the 5.2 branch.

Reviewed by desrosj, SergeyBiryukov.
Props onlanka, Rarst, mukesh27.
Fixes #47304.

[spacedmonkey]

Related: #4575