Drupal 8.x

I want to configure the sale of keys, each key must be unique for each client.

What am I doing:
I have a program for windows on c #, through it, the user is registered. When registering through Restfull, the user field field_mac is populated, in the field_keylicense field I generate a key using my module.
Question:
How can I sell a given key using the module commerce .

Dear all,

I hope you can help me with this strange error.
I have a large website that is running quite well, except for one thing: I can't run Cron from the UI. This is quite painful, but also mysterious because the scheduled crons (every 3 hours) just run as far as I know.

When I do run Cron from the UI I get the dreaded "unexpected error" message. In the 'recent log messages' I find this:
 

Salve

Volevo sapere come è la procedura per aggiornare drupal dalla maggiore release 8.x alla 9.x senza usare ne composer e ne drush ?

Grazie in anticipo per la vostra collaborazione e risposta

Hi,

I've created a content type for product reviews. One of the fields of the products is a taxonomy term. E.g. in the taxonomy "Genre" there is "comedy" or "horror".

I would like to find a way to show the related content by the taxonomy term associated to the product.

For example : on the page of the review (content) of a movie (product) of the horror genre (taxonomy), I'd like to show other horror movie reviews. I've tried to work with contextual filters in views, to no avail so far.

Thanks

I would like to create a block in a custom module and have the block display a form or some text but not both. How would I determine if the form was submitted successfully so the code could either return the form or the text? 

If I run composer require drush/drush on a brand new out-of-the box D8.8 or D9.0 site (on shared hosting), then it will mostly FAIL with less than PHP memory_limit = 2768Mb (always fail with less than 1 GB).