Upgrading Drupal

I tried updating my Drupal 8.3.7 to 8.5.1 unsuccessfully so I reluctantly decided to just install a clean instance of Drupal 8.5.1 and copy/paste my content from my old site to my new. I notice that the views I created in 8.3.7 had this option:

REST EXPORT SETTINGS    Provide a REST export

and my 8.5.1 instance no longer has this option. In the previous version I was able to set up a path, like "/api/alerts"

To update from drupal 6 to drupal 8 at once? or do I have to go thru drupal 7 first?

Please consider me a newbie, but I've been working through installation of composer and drush to permit an update to Drupal 8.5.1 today. I worked through all the normal operations and followed tips and tricks found in tutorials and support tickets all over this wonderful forum. Presently, I'm FREAKING OUT because while the composer update appeared to work just fine, when I go to the website I only get:

I have a palantirnet/drupal-skeleton composer.json created D8 site. What I did to update are:

1. Run `composer remove drupal/core` so that no dependency issues would cause errors
2. Run `composer require drupal/core:^8.3`

On an Acquia Dev Desktop setup of the site everything looks good but when I used the Docker php:5.6-apache + drush/drush image, I'm getting an somewhat serious warning when running Drush commands like st, updb, cim and cex. Here are the messages:

I tried updating my packaged distro of 8.2.7 straight to 8.5.1 and I ended up getting "The website encountered an unexpected error.

I am trying to get the entity updates to run after updating to 8.5.1 I have the following on the status page:

Mismatched entity and/or field definitions
The following changes were detected in the entity type and field definitions.
Content moderation state
The Content entity type ID field needs to be updated.
File
The URL alias field needs to be installed.

When I try to run entity updates I get the following error: