PHP 7 & AH00124: Request exceeded the limit of 10 internal redirects

Hi !

It is time for us to upgrade to PHP 7 (curr. 5.6) on a mutualised host where we get a 4.9.8–fr_FR wordpress running fine since years.

But switching to PHP 7.x results in an error :

>
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at [no address given] to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.
Apache/2.4.10 (Ubuntu) Server at http://www.combustible.fr Port 80

When I look in the error log, I find something like :
apache2[4]: [core:error] . . . AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use ‘LimitInternalRecursion’ to increase the limit if necessary. Use ‘LogLevel debug’ to get a backtrace.

I’ve tried to use LogLevel debug’ for no more information in the error log.

In order to investigate a bit, I’ve changed the theme to Twenty Eleven : same error.

I’ve then turned off each extension one by one : same error.

‘PHP Compatibilty Checker’ says everything is OK for all active plugins and extension.

Here’s my .htaccess, I guess it’s where something’s going from but can’t figure out what although I already tried some changes in it. Any help appreciated, thanks!

AddType application/x-httpd-php5 .php

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ /index.php/$1 [L,QSA]
</IfModule>

# END WordPress

The page I need help with: [log in to see the link]