Fata Error with The Post Grid

Hi there!
While updating The Post Grid, I encountered the error:

Fatal error: Uncaught Error: Call to undefined function determine_locale() in /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-content/plugins/the-post-grid/app/RtTpg.php:132 Stack trace: #0 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-content/plugins/the-post-grid/app/RtTpg.php(127): RtTpg->load_language() #1 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-includes/class-wp-hook.php(286): RtTpg->init_hooks('') #2 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array) #3 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #4 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-settings.php(450): do_action('init') #5 /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-config.php(93): require_once('/home/users/wyd...') #6 /home/users/wydawn03/public_html/dom in /home/users/wydawn03/public_html/domains/wydawnictwoj.pl/public_html/wp-content/plugins/the-post-grid/app/RtTpg.php on line 132

The error locked me out of the WP dashboard and there is nothing I can do. I am not a developer or an IT specialist. The website I run is built on the Twent-Seven theme, but only as a platform – I created the website with Elementor.

Can you help me with fixing the problem so that I can access the dashboard and also help me solve the problem with the FATAL ERROR?

Thank you in advance,Tomek

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