client sent plain HTTP request to HTTPS port while reading client request headers

[basti]

Hello,

after i switch my error log to info level (to find an other Problem) I
get a lot of messages like:

"client sent plain HTTP request to HTTPS port while reading client
request headers"

I search for a solution and always found that this error is shown when
http and https is in one server {} but my config looks like the
old-fashioned way.

server {
  listen      443 ssl;
  server_name your.site.tld;
  ssl         on;
  ...
}

server {
  listen      80;
  server_name your.site.tld;

  return 301  https://your.site.tld$request_uri;
}

I have switch the order of hhtp and https server{}, the error is still
the same.

I have also try "error_page  497 https://$host:443$request_uri;", the
error is still the same.

I cant reproduce them, i have try to connect the site via http and also
via https and grep the log for my IP but I found nothing.
How can I fix that?

Best Regards,