403 Permissions denied

Are you logging in with a username that has super admin capability?

Can you at least get to the Network Admin page without error?

Got into your database and navigate to the wp_sitemeta table. In this table, you should find the site_admins meta_key. In the value you should see something like this: a:1:{i:0;s:7:”admin”;}. Do you see it?

You should check with your hosting provide to make sure that there is no issue with your hosting account.

Ok, and how about the value for wp_capabilities in wp_usermeta. It is looks like this: a:1:{s:13:”administrator”;s:1:”1″;}, its ok.

Is this a new install? If not, was it working before? Did you recently upgrade it or a plugin or recently activated a plugin that could be causing the issue?