php - WordPress https redirect loop -

i'm trying setup wordpress blog subfolder on domain using ssl without success. if blog .htaccess set redirect http https results redirect loop. if .htaccess not set redirect http https blog not showing browser blocking http requests ssl in use, wp logins failing in case.

details: - fresh wordpress installation - domain using ssl - wp installed on subfolder example.com/blog/ - https set wp's home , site url in database 

here blog folder .htaccess

<ifmodule mod_rewrite.c> rewriteengine on  rewritecond %{server_port} !^443$ rewriterule (.*) https://%{http_host}%{request_uri} [r=301,l]  rewritebase /blog/ rewriterule ^index\.php$ - [l] rewritecond %{request_filename} !-f rewritecond %{request_filename} !-d rewriterule . /blog/index.php [l] </ifmodule> 

here main domain .htaccess:

options +followsymlinks rewriteengine on rewritebase /  rewritecond %{http_host} ^www\.(.*)$ [nc] rewriterule ^(.*)$ http://%1/$1 [r=301,l]  rewritecond %{request_filename} !-d rewritecond %{request_uri} !\..+$ rewriterule ^(.*)$ http://foobar.example.com/$1 [l,r=301] 

here apache config http requests: /etc/apache2/sites-available/000-default.conf

<virtualhost *:80>    servername example.com    serveralias *.example.com    serversignature off    rewriteengine on    rewritecond %{https} !=on    rewriterule .* https://%{server_name}%{request_uri} [ne,r,l] </virtualhost> 

any , ideas check highly appreciated.

update: have manually replaced http urls https in wp database, occurrences sample page , post urls, didn't resolve problem.

i able resolve problem adding $_server['https']='on'; wp-config.php. don't know why $_server['https'] not set system, guess somehow related apache/ssl configurations.

without setting $_server['https']='on' wp not able detect https , loading content on http .htaccess redirects caused redirect loop.