Drupal 8.x

I have a Drupal 7 website with hundreds of nodes inserted and I realized that for my specific needs I have to migrate to Drupal 8.
Is there any way to import Drupal 7 to Drupal 8 Nodes in * .csv (or other methods) safely without anything being lost?

P.S. I have seen that there are many modules but I would need some sure advice

Best Regards

i m trying to develop a community website where youth will be able to register online and express freely. At a same time, the organization availing this platform need to provide various useful information to youth. And some advertisements..

I have a view with a table of published nodes that is available to all users. I would like each user to be able to select specific nodes from the table to show on a separate view with only nodes the current user has selected. The view that is global may have 150+ nodes, How do I allow each user to select a few nodes to show on a table specific to the current user?

Like a shopping cart of sorts where the user selects their items to show in the cart but it would not affect any other user viewing the items. Only I am only trying to create a watchlist for each user.

Drupal 8.8.5
I have done a lot of research on the web on how to retrieve the data of an entity reference field. But the code I found on version 8.8.5 doesn't work.
Before sending I have to read the value of the entity reference field. With kint I have seen the depth of the arrary but it does not return the value.
The code I use is this
$ a = $ form ['field_localita_rientro_ca'] ['widget'] [0] ['target_id'] ['# value'];
but I get this error back
Notice: Undefined index: #value in udf_form_alter ()
I have tried everything but nothing to do.

Hi all! I'm pretty new to the admin side of Drupal, have been using Drupal since version 7 as an editor and "junior" admin.

I have a problem that I'm not sure is fixable. 
We have updated a module on our Drupal 8.7.7 site and now get a white screen when trying to login. Before doing the update we made a backup of the directory files but not the database (I know, very very very stupid). We have earlier database backups but it can be quite a lot of work to find out what has changed since that backup (about a month ago).

Hi!

I am developing my first website on my local PC Windows 10. I have some mp4 video files need to upload to the site, but they are all above 2MB maximum allowed upload size. I followed the instruction from a previous topic: https://www.drupal.org/forum/support/post-installation/2017-08-16/how-do-i-increase-the-maximum-file-upload-size , still can't change 2MB limit to a higher number like 40MB.