Upgrading Drupal 7.43 to 8 error: Source database is Drupal version 8 but version 7 was selected

Question

I am new to Drupal, but I am trying to upgrade a site with the version 7.43 to 8, flowing these steps: https://www.drupal.org/docs/8/upgrade/upgrade-using-web-browser

After installing the Migrate modules and defining the source site, I have the following error message:

Source database is Drupal version 8 but version 7 was selected.

In my old site's database, the drupal_version table is empty.

Answer 1

I managed to solve it. It was caused be an update on PHP, that caused blank pages or “white screen of death” (WSOD) in the admin, too. After updateing to 7.59, it was OK. This article helped me: https://www.drupal.org/node/158043

Conclusion: first update latest 7.x than 8.