Error loading mainpage after installation this plugin

Hello!

I recently installed Ultimate Member 2.5 to my site. Upon activation of this plugin, my main page failed to be loaded. Error message shown as follow:
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Notice: Trying to get property 'ID' of non-object in /www/wwwroot/www.friends-exchange.com/wp-includes/class-wp-query.php on line 4213

Notice: Trying to get property 'post_title' of non-object in /www/wwwroot/www.friends-exchange.com/wp-includes/class-wp-query.php on line 4215

Notice: Trying to get property 'post_name' of non-object in /www/wwwroot/www.friends-exchange.com/wp-includes/class-wp-query.php on line 4217

Oops! That page can’t be found
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Anyone know how to solve this ? Thank you