I did have this:
ERR_MAUTIC_3_MIGRATIONS_IDENTIFICATION_FAILED: We couldn’t reliably detect the amount of available database migrations. Please try again by refreshing this page.
However, I think that was more to do with a PHP timeout, as it all went through fine after I refreshed. I’ve also updated the timeout settings in php so scripts can run for 240 seconds just in case it causes issues in the future