Blog/Home Page

Hi @col_blimp,

Because WordPress makes users use “blog page”, “blog category”, “page”, “home page”, “front page”, “posts page”, “is_home()”, and “is_front_page()” (among many others) interchangably, I have a difficult time understanding your comments.

But, I’m conjecturing your literal “blog category” has the same ID as the literal “front page” set in your site’s Reading settings. Unfortunately, without a link to your site, I can’t verify this for you.

In any case, I suggest reassigning the home page to a newly set-up page, so it gets a new ID. Then, you should (permanently) delete the old one to resolve this.

Your conjecture was spot on, both an id of 5, how that occurred I don’t know but thank’s.

I’ve seen this issue many times, and I thought only CPT could cause this… until I’ve experienced it on self-built and close-to-vanilla-WP site running on my own VPS last week.

So, I decided to dig into it, and I assimilated the following (technical!):

I think it happens because WordPress tries to use an incremental ID system… throughout multiple database-tables… via mysql_insert_id(); but, when the last attempt fails, it resets this value, and then it lets the database decide based on the used column without fixing it beforehand.
Then, when a table with the highest number is active again (after using /(insert|delete|update|replace)/), it’ll be corrected automatically.

All of the above can happen with one click on the “new post” button, and the user isn’t informed. It’s very complex, and I could’ve missed the cause by a mile.

Nevertheless, here are my sources; I should create a “core.trac” ticket once I can reliably replicate this:

1. Call: https://github.com/WordPress/WordPress/blob/4.9.6/wp-admin/post-new.php#L70
2. Test & create: https://github.com/WordPress/WordPress/blob/4.9.6/wp-admin/includes/post.php#L608
3. Start inserting: https://github.com/WordPress/WordPress/blob/4.9.6/wp-includes/post.php#L3446-L3452
4. Failure detected, but we continue inserting anyway: https://github.com/WordPress/WordPress/blob/4.9.6/wp-includes/wp-db.php#L1860-L1862
5. Use failed ID: https://github.com/WordPress/WordPress/blob/4.9.6/wp-includes/post.php#L3453