SOLVED – Migrating from Siteground don't work

Think it was a plugin causing the problem… sorry
Hi, I have migrated a small site for testing the hosting on wpmu, the site had 2 issues when I started:
My original site is on MySQL v5.6.40-84.0-log whereas is on MySQL v10.3.20-MariaDB-1:10.3.20+maria~bionic.
The original site uses apache whereas uses nginx.
The site is installed with DIVI, and the builder is not working, I get the error:

ERROR: It had not been possible to open the file. Review your name and your permissions

And the pages look nothing like they should.
Is there some known issues regarding migrating from siteground, or Divi?