Upgrading Drupal

I'm trying to migrate D6 to D8 using the migrate modules in D8; however, the D6 Taxonomy tags are not being imported.

I did get the following error:

Migration d6_term_node_revision:11 did not meet the requirements. Missing migrations d6_term_node:1, d6_term_node:6. requirements: d6_term_node:1. requirements: d6_term_node:6.

Operation on Term/node relationship revisions failed

After updating to Drupal 8.3.7 the following error reports when I run update.php :

"Plugin not detected
Panelbutton requires the plugin.js library. Download the plugin from http://ckeditor.com/addon/panelbutton at least version 4.5.6, and place it in the libraries folder (/libraries/panelbutton)"

Plugin is downloaded. However, I can not find a "libraries" folder to put it in...

I try to update drupal after having installed last drupal 8 core.
But I can't run all the update

here is the list of database update

system module
Update entity displays to contain the region for each field.
Force caches using hashes to be cleared (Twig, render cache, etc.).
Force plugin definitions to be cleared. @see https:www.drupal.orgnode2802663

Hi, sorry if it's quite obvious for most of you, but I have a question, more than a problem, about the changing of release and updates.
I've installed the 8.0.0 and have the warning to upgrade to fix some security vulnerabilities. I have a list of securities updates and a suggested release to use. Is it not possible to install the needed softwares directly in the existing website, like in other CMS? It seems I can only download the folders in my client PC and then use those as if I had to install Drupal for the first time.
Thanks.

Hello, I am new to the forum, I have the following error when performing update.php, the page appears blank and through the inspector I report the following errors, somebody can help me

Hello.

After upgrading from 6 to 7 versions of Drupal and at login to site, I see warning:

Notice: Object of class stdClass could not be converted to int in function drupal_write_record() (string 7340 in file /home/u3654/domains/my_site/includes/common.inc).

And also the user has lost the avatar. Errors during the upgrade was not.