Drupal 8.x

I need help with Search API Views exposed form. I want to make hierarchical select in a taxonomy tree. I tried Simple Hierarchical Select, https://www.drupal.org/project/shs but it does not work with Search API. I tried Client-side Hierarchical Select, https://www.drupal.org/project/cshs it didn't work at first but going to try it once again maybe I find a workaround.

I tried different ways to migrate Drupal 7 to 8, There are lot of errors at different levels. Not sure what is the correct way to go forward. 

While migrating using UI, most of the modules are not supported by 8. I need alternate modules so i can run my system.

As per instructions:

- Installed Migrate Tools
- Installed Migrate Upgrade
- Installed Migrate Plus
- Installed Commerce Migrate and Commerce Migrate Commerce
- Prepared a fresh copy of Drupal 8 site with all required module enabled

Uncaught PHP Exception InvalidArgumentException: "The URI '/kultur/news/news/a/1505878.html' is invalid. You must use a valid URI scheme." at /home/hopfrog/public_html/core/lib/Drupal/Core/Url.php line 290

The site no longer works. This is the only error (in error.log). How to fix it?

Thanks

Webform contact form default ones email field validations not working if some one type wasojofy@mailinator without .com it still accepting and submitting the form

Can someone help me understand how or what is the best approach for upgrading a drupal site from 8.7.x to 8.9.x / 9.x. (Community recommended to upgrade to 8.9.x first and then to 9.x)

How can a non profit organisation plan the frequent upgrades coming up?

We have about 50 contrib modules to be updated, Also to upgrade to 9.x, 40% of existing contrib modules are not available.