Hi, I'm using 1.3.58 - basic
Master site: www.mettecosmetique.se
Slave site (1 of 7): nimue.se/

I've recently upgraded my Joomla to 3.5.0 and on all my slave-sites,
I've run "Fix database", cleared all cache and purged all converted file but still I get:
Fatal error: Cannot redeclare contentBuildRoute() (previously declared in /home/mettecos/public_html/components/com_content/router.php:483) in /home/mettecos/public_html/components/com_multisitescontent/multisites.router.php on line 496

Anyone?

I will try to reproduce.

I've solved it (panic solution) by commenting out the following in /components/com_multisitescontent/multisites.router.php:
/**
* Content router functions
*
* These functions are proxys for the new router interface
* for old SEF extensions.
*
* @param array &$query An array of URL arguments
*
* @return array The URL arguments to use to assemble the subsequent URL.
*
* @deprecated 4.0 Use Class based routers instead

function contentBuildRoute(&$query)
{
$router = new MultisitesContentRouter;

return $router->build($query, $site_id);
}
*/
/**
* Parse the segments of a URL.
*
* This function is a proxy for the new router interface
* for old SEF extensions.
*
* @param array $segments The segments of the URL to parse.
*
* @return array The URL attributes to be used by the application.
*
* @since 3.3
* @deprecated 4.0 Use Class based routers instead

function contentParseRoute($segments)
{
$router = new MultisitesContentRouter;

return $router->parse($segments, $site_id);
}
*/

I know this source, but the problem does NOT comes from there but from the core of joomla that is perhaps changed and cause an incompatibility issue.
So I need to be able reproducing it with a debugger to understand what in the core of joomla cause that.

Yes, I understand that, like I wrote it was just a quick fix (perhaps can help someone else in the same situation)
Will you post in this thread when you find the solution or should I keep my eyes open for an update?

Becarefull that the file "multisites.xxx" are removed when you do "purge".
So your "panic fix" can be removed at any time.

I have noticed the problem and started to prepare an environment to reproduce it.
This may take a little time.
Thank you to have reported this issue.