Show ACF field with link to ultimate member profile/WordPress user profile below the post (single post layout)

I’m using Advanced Custom Fields and I’m trying to show a custom field below the single post. I managed to get the code to render below the post, but when I set the field movie_actors and save, the entire page goes blank after I refresh it, it doesn’t show any errors on the screen although I already have debug mode enabled.
My field is set as User Object inside ACF, and the field type is user.
What I’m trying to do is to show a link to the user profile in Ultimate Member. I also tried to show a link to the default wordpress user profile just in case, and it also gives me the same result.

Posts title instead of Pages and Category titles – PHP WordPress

In order to have two blogs on one website, I was able to put in the menu two categories: DOCUMENTATION and ACTUALITES.
My problem is in the header. The titles are displayed well however for both categories, the titles correspond to the title of the last article of the page…
You can see an example in the picture (You will see that the CONTACT page is OK but for the DOCUMENTATION and ACTUALITES pages the titles are those of the last article).
I would like to replace these article titles with those of the DOCUMENTATION and ACTUALITES categories.
I think I have found the problem code but I don’t know how to solve it.

AWS Lightsail WordPress – connect to database on instance using mysqli

I have a wordpress website hosted on AWS Lightsail. On that website, I would like to use a shortcode to retrieve data from a database using mysqli. However, everytime the script that connects to the database is executed, I receive a connection error. The database is on the same AWS Lightsail instance.
I was wondering if I need to establish an SSH-tunnel because this is also needed if I connect to phpmyadmin. But since the script is executed on the server itself this does not really makes sense in my understanding. I have used the exact same code on a local host and it worked perfectly fine. What am I missing here?