There are 2 essential safeguards that your : First , block Googlebot. Make it so that Google cannot read the new content until the validation is complete. This is necessary and allows you to breathe easy.
You migrate, validate and only
When you see that everything is perfect do you let Google see your new content. There are different ways to do this. We try to be almost autonomous and not ask IT for strange developments. But you have to foresee it and do it before anything changes.
The second is to calculate and guarantee
The rollback warning time. There are migrations that are a disaster. This is how it is. A simple comma add at the last minute, a file that someone forgot facebook database to upload or any server feature that nobody took into account.
What do we do when we know that
Google is going to take what is on the web very badly and there is no prospect of fixing it in time? Go back. It is hard, but there is no other option than know the results to return to the previous version, give a couple of days to solve the problem and go back up. It is the healthiest thing to do. However, the more time passes, the harder it can be to make this decision.
Therefore, SEOs must commit
To a maximum rollback time , a time in which they must already rule out this possibility. This time can be different in each project but it must be defin. Generally, we are talking about a few hours, the time to do a crawl of the essentials plus manual validations.
A migration never ends with the first change
Things are always correct afterwards. These are not always SEO aspects, so it often happens that there are modifications that SEO or even development snbd host are not aware of. That is why it is essential to revalidate first daily and then weekly that everything remains in place.