Meta data not saving?

Hi all,

I’m desperately trying to fix a fault on by WordPress site. I have been at this for days now, but am clearly unable to solve it, so I would sincerely appreciate any help! I have already posted a couple of times requesting help but had maybe not investigating or researched enough.

The issue is that the Featured Image is not saving, nor are, for example, the meta data for the All In One SEO tags such as title, keywords, etc…

I had initially replaced all the WordPress files, this did not help, I tried disabling all the plugins, this did not help and I also reverted back to the default theme, this didn’t help either.

I enabled debug and saw an error message that I think could be related which is:

WordPress database error: [Duplicate entry '132090' for key 1] INSERT INTO wp_postmeta (post_id,meta_key,meta_value) VALUES (4168,'_edit_lock','1395408463:1')

I have setup a new site and installed WordPress, the theme and all the plugins and a earlier backup of the database and this works OK, therefore I can only assume that there is an issue with the database in some form.

I have reached my level of knowledge with regards to MySQL databases and could really do with some assistance on how to combat this issue.

Any help would be greatly appreciated!