fatal error-I can't login in

Hi,

Did you by any chance happen to make a backup of your WordPress files and the database before updating? (if you don’t actively make backups yourself then maybe with some luck your host does this automatically for you)

when you say WordPress 3.5.1, do you actually mean 3.5.1 or the latest version which is 3.9.1?

If you were updating from 3.5.1 to 3.9.1 there could have been a problem or conflict that occurred during the update that caused the fatal error. And as far as i know the only way you could recover from this is by using a old WordPress release (3.5.1) getting your WordPress active again and then deactivating all plugins and then try updating WordPress again first, and then your plugins (update before reactivating plugins). But this would entirely depend on if you have a working version of your database.

If you haven’t made a backup of your WordPress website, now is a good time to use an FTP client to backup your WordPress files, and then login to your Hosting cPanel and make a backup of your MySQL database

??

If you haven’t backed up, do that now before you do anything else

I have a similar issue – can’t upgrade client site from 3.5 to 3.9.
There’s no option in the dashboard – maybe because it’s skipped too many updates?
ALso, plugins are not showing in the dashboard, or users…

I have taken a cpanel backup – do i have to manually upgrade via ftp???

If you have backed up your database and files then yes go ahead and update via FTP.

However it sounds like you have a different issue: if you can’t see users or plugins or an update button it is because you are not logged in as an administrator or something is wrong.

I would start a new topic called can’t upgrade client site from 3.5 to 3.9. They will be able to help. Just copy and past what u write here, a new topic will get ur problem solved faster and since it’s slightly different deserves a better answer than I have.