All of the sudden my WordPress site wouldn’t allow me to access the wp-admin. Once I logged in, it would just redirect me to the homepage.

I tried disabling plugins, changing themes, and doing rain dances, all to no avail. It appeared that the problem was coming from the database. I cleared out all the transients in wp_options and a bunch of other junk but that didn’t help. I cleared out all 300,000 users in wp_users and that didn’t help. Suddenly it came to mind that there may be a problem with the wp_usermeta table that appears in phpmyadmin to be “in use”.

I had to drop wp_usermeta and create it again, then added the fields:

• unmeta_id – leave this blank (it will be auto-generated)
• user_id – this will be the id of the user you created in the previous step. Remember we picked 4.
• meta_key – this should be wp_capabilities
• meta_value – insert this: a:1:{s:13:"administrator";s:1:"1";}

Insert another row with the following information:

• unmeta_id – leave this blank (it will be auto-generated)
• user_id – this will be the id of the user you created in the previous step. Remember we picked 4.
• meta_key – this should be wp_user_level
• meta_value – 10

Now it works.