Error updating from sw6 ea2 to 6.1

Hello everybody!

We are trying to update from ea2 to 6.1 but we are getting this error when running the update on database migration step:

Received an error message.
URL: applyMigrations?offset=0&total=0&modus=update
Message: Internal Server Error
Please try to fix this error and restart the update.
{"code":0,"message":"Unable to load migration Shopware\\Storefront\\Migration\\Migration1569482074AddProductMainCategory at path ...file...vendor\/shopware\/platform\/src\/Core\/Framework\/Migration\/MigrationCollection.php

Does anyone have an ideea how we can fix this?

Thank you in advance!

Best regards,