When not updated correctly, site migration from http to https can cause significant changes in how Google views and ranks your site. The involved steps, such as updating your internal links and accessing htaccess files are not simple tasks and should only be carried out by someone who is experienced and trained in these particular disciplines. You shouldn’t try to make these amends yourself if you are not professional.
When a site changes from http to https then this is viewed by Google as if the site has an entirely new domain e.g. changing from cxmarketing.com to wearecx.com. By adding an SSL certificate to your site you are removing all the links and pages that Google finds familiar and, when it tries to send people to these pages, will return nasty 404 or similar errors, before eventually deranking these pages and no longer serving them in search results.
Google user searches for “ABC SEO Agency”
Google serves the web page it has crawled, indexed, knows and loves. http://www.abcseo.com
When the user clicks, that page no longer exists, it has been replaced by https://www.abcseo.com instead.
But Google has no idea that this page exists. The user gets a 404 error message. Google logs this as a bad user experience and thinks… ‘Well, I won’t send anyone there again.” Hey presto, your search rankings drop through the floor. The http to https SEO impact can be seen straight away.
All of the work that you have done in helping Google identify and rank the pages on your current site could be undone overnight with a migration to https if the correct steps are not taken.