The reason why you hitting this is because from Joomla 3.6.3 onwards improved validation of JSON data stored in the database (Usually as params for extensions). Unfortunately, this means that after updating, sites with invalid data can can become inaccessible.

The usual error message shown is:

0 - Error decoding JSON data: Syntax error

I suspect your #__users table contain those invalid JSON data from your database, can you provide us with your database access for your staging site so we can better have a check?

BY the way, your FTP user account seems like not link to your staging Joomla root folder.

Thanks for the response, Arlex. I've updated the credentials with this ticket with a new FTP user with access to the staging folder (just go to the staging1 folder rather than public_html). Also I gave access to phpmyadmin. Please let me know if you need anything else.

I already help you updated those invalid JSON string to valid now, can you give it a check is it work fine now?

Looks to be working great to me! One last thing - I've been doing some pretty heavy modifications to the site tonight and would like to just have that change applied to the production site.

Could you make that same update to the live DB? I would myself but I don't see which table you are editing from that screenshot.

I added that user I gave you with permissions to the live mysql database, so if you login in the same way you can edit it as well.

Perfect, you're the best Arlex! Ran that query and the site updated perfectly. Thanks so much for your help!

Hi there,

You are most welcome. Glad to hear that your issue has been resolved now.

As a gentle reminder, kindly start a new thread if you have any other issue in the future so it will be easier for us to manage your inquiry. I will lock and mark this thread as resolved.