The problem Nextcloud HTTP header "Strict-Transport-Security" is not set to at least “15552000” seconds.

The following guide on a very simple solution to the problem nextcloud:

HTTP header "Strict-Transport-Security" is not set to at least “15552000” seconds.

Just edit the file .htaccess.

We log into our ftp server and edit the .htaccess file by adding at the beginning:

<IfModule mod_headers.c>
      Header always set Strict-Transport-Security "max-age=15768000; includeSubDomains; preload"
</IfModule>

Header always set Strict-Transport-Security "max-age=15768000; includeSubDomains; preload"

</IfModule>

That's it 🙂