WordPress 5.0.3 and Portum 1.0.6

Hello.

I installed WordPress 5.0.3 and Portum 1.0.6. Pictures are not displayed on the main page of the site. Please help.

My site: http://tenderassistant.ru/

tenderassistant.ru [Fri Feb 01 02:46:06 201] [error] [client 94.41.71.220] PHP Catchable fatal error: Object of class WP_Error could not be converted to string in /home/srv64375/tenderassistant.ru/wp-includes/formatting.php on line 3796”

hey there

First of all, i can see error 500 in the error log, “Failed to load resource: the server responded with a status of 500 (Internal Server Error)” so its good idea to investigate this case with your hosting,
If you still cant find the solution please enable debugger in wp-config.php to see the
Can you check what happens with the default WordPress theme?
Not sure if this is a theme problem or not, the error message is coming from WordPress file if there is anything to update go ahead and update everything