We faced two situations where a website didn’t get as much Google traffic as before after moving the website to HTTPs. Here is one of the google analytics history report of one of the domain. We moved this domain in may 2017. Unfortunately, there is a peak that may mislead you. In fact, it was during the French presidency and the blog discussed French politics. Following the French presidential elections, the organic google traffic dramatically dropped.

Before switching to HTTPs the domain used to receive 150 visits on a daily basis. After the switch, it received 50 visits. It was a 67% traffic loss. However, we didn’t change the theme. We didn’t change the URLs. We didn’t change the content. It was a WordPress website and we haven’t added any special plugins or coded anything. This blog is quite popular and we know that major other blogs still link to it. For sure, the links of the old blog go to
Here, we expected an improvement that’s why we waited. We checked if we had mixed content errors. Our Sitecozy link scanner scanned the whole website without finding mixed content errors. That’s why we think that webmasters should not systematically move to HTTPS
The safest solution would be to create 301 redirects for the sections of the website that need a SSL certificate: E-commerce, shop, back-end.