WordPress not auto saving all articles on my main site.

   Recently the autosave feature wasn’t working well on o6asan.com though I cannot recall from when. o6asan’s soliloquy and o6asan’s soliloquy-part2 have no problem.

   Apart from this, I found a lot of “WordPress database error Duplicate entry ‘0’ for key ‘PRIMARY’ for query INSERT INTO `WordPress DB table name` ～” on the Apache error log when I checked the errors about php_opcache.dll on August 29.

   Yesterday, I suddenly remembered the errors on the Apache log, and began to get the solution. I saw a lot of sentences related to Notes when I looked into the log again. At the time, I first recognized this errors and autosave feature had a strong relationship. Besides, the errors began on August 23. I must have done something wrong at updating MariaDB. (-_-;)

   I saw what table names the log included, then found them out, i.e. `wp_postmeta`, `wp_posts`, `wp_redirection_logs`, `wp_sitemeta`. I logged in phpMyAdmin and compared wp_postmeta structure with wp_2_postmeta one. Because wp_2_postmeta has no problem. Finally I noticed wp_postmeta had no AUTO_INCREMENT in meta_id’s extra field. I also looked the rests had the same problem.

   First I backed all data up then tried and fixed them.

1. Select wp_postmeta table.
2. Select ‘Structure’ from Menu.
3. Select ‘Change’ from Action of meta_id.
4. Check ‘A_I’ box on and save.

   If you use CUI, I think you can use the following.
ALTER TABLE `your WP DB name`.`wp_postmeta` CHANGE `meta_id` `meta_id`
BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT;

   I did this for `wp_postmeta` and `wp_posts` without difficulty. But for `wp_redirection_logs` and `wp_sitemeta`, I had the following error.
#1062: ALTER TABLE causes auto_increment resequencing, resulting in duplicate entry ‘1’ for key ‘PRIMARY’

   `wp_redirection_logs` table has just logs of the plugin Redirection. So I emptied the table and did the above steps again. If you use CUI, I think you can use the following.
TRUNCATE `your WP DB name`.`wp_redirection_logs`;

   But I need the contents of the table `wp_sitemeta`. So, I first emptied the table and did the above steps again. Then I clipped `wp_sitemeta` INSERT statement out from the back-up sql file and imported it to the table.

   The errors on the log file have gone and the autosave feature works well now. Mission complete!

   Don’t trust me too much because I handled the errors in my own fashion. m(_”_)m

Edit(Sep.6):
   When I updated to BulletProof Security .50.8, I had a trouble that the Notice “Network/Multisite BPS plugin Network Activation correction:” had not gone away. So, I went talk to the forum. Then I resolved the problem with his help. This trouble is related to the AUTO_INCREMENT missing again. I think it is maybe caused by phpMyAdmin bug that I read several days ago. But who knows about the truth? Sigh.

   Anyway, the Notice has gone. Now I can sleep in peace (^_^;).