Drupal 8.x

I am using 8.5.10 based on drupal-composer/drupal-project because some of the contribution modules do not correspond to 8.6.
I will update it to 8.6.9 soon.
Generally, in large spaced versions, is it okay to run composer update at once?
Is it better to update to 8.6.9 after updating to 8.6?

So, I am moving from Drupal 7 to Drupal 8.....

I have done some migration, but Themes were not automatically migrated....

Now, I have a Drupal 8 multi-site with some 12 sites - and Synchronization Import - Fails for all of them.... due to 2 old, unused Themes from Drupal 7, which actually cannot be ever even installed on the 8th version....

I am now unable to export/import even single Views, due to some non-existant Themes from Drupal 7....

What should I do?!

How to uninstall Themes which never even existed or can exist in current version Drupal 8?!

Hi All

I get the idea of needing to write user pics and images, but the world-writable sites/default/files has always bothered me; I'm paranoid.

But looking at my new version 8 install I see a sites/default/files/php/twig subdirectory containing a sea of various alpha-numeric subdirectories all world writable.

Is this normal/expected behavior; can I remove the world writeable bits on these?

Impressions: After searching to download a tarball with the actual version number in the filename (as opposed to "latest") I installed drupal-8.6.9.tar.gz -- cool, no problem, I have the basic/standard site up and install, playing with the Bartik theme.

My first surprise is that the site seems slow -- much slower than my Drupal 7.x sites and I haven't even started adding modules. But no problem, so I decide to add a simple HTML block.