Can't make new post, error on Avia Template Builder and Post.php

Hello,

My site is having error since i migrated it from another URL.
Almost everything works fine, except when i will add new POSTs.

I cant add any content at all on POSTs, and it shows the following erros messages:

On top of the dashaboard it shows:
Warning: Creating default object from empty value in /home/storage/0/40/28/site1369335934/public_html/wp-admin/includes/post.php on line 708

And on the bottom, at the space to add texto of POSTs, its says:
Catchable fatal error: Argument 1 passed to AviaBuilder::handler_wp_dbx_post_sidebar() must be an instance of WP_Post, instance of stdClass given in /home/storage/0/40/28/site1369335934/public_html/wp-content/themes/olharclinico/config-templatebuilder/avia-template-builder/php/template-builder.class.php on line 330

My php version is 5.6, theme version is 4.5.4 and wordpress version is 5.1.2 – Everything exactly as my working version on a temporally url.

Already tried to turn off plug-ins, i even uploaded again the wp-admin/theme folder from the working site and nothing changed.

Also there is a funny thing, i cant create new users, when i try to create new users on the site, it don’t give any error, but don’t create the user.

Can someone give me some advice or tips on how to fix?

Thanks