Hi,
I’m working on Kirby 3.4.2. Everything was fine and then suddenly my pages section didn’t show anymore.
I got this error:
La section « primarypages » n’a pu être chargée: Argument 2 passed to Kirby\Cms\Blueprint::normalizeColumns() must be of the type array, string given, called in C:\wamp64\www\ms-avocat.com\kirby\src\Cms\Blueprint.php on line 694
Hm, I tested your blueprint and cannot reproduce this. Check if your indentation is somehow wrong or if you are mixing tabs and spaces (yaml files should use spaces for indentation only, not tabs).
I found out what was the problem. I created a new template with a new blueprint and it broke everything. I deleted the pages and the blueprint and recreated it from scratch. Now it works well.