I have recently discovered a rather weird problem. My Joomla front page is the Jomsocial front page and when I login on the front page Chrome gives me the Too many redirects error. It doesn't happen with all users, my own super user can login fine but newer super users and normal users get this error. And everything works fine when you aren't logged in.

I used the Network tools in Chrome to see what the redirects did. If I first try to visit dev.fotoforalla.se (no SSL) it gives me a 307 internal redirect since I use HSTS, that is as it should be. So that redirect takes me to dev.fotoforalla.se (SSL). But after that I get a 302 redirect that takes me back to dev.fotoforalla.se (no SSL) and the redirect loop starts.

This only happens on the Jomsocial front page so I'm wondering if it's Jomsocial that is causing this 302 redirect that shouldn't happen and if I can fix it?

I solved it! The problem was that I had set Joomla to use MySQL PDO and ModSecurity was blocking me from seeing the error message. When I turned of Mod Security I got this error message:

YOU CANNOT SERIALIZE OR UNSERIALIZE PDOSTATEMENT INSTANCES

Doesn't Jomsocial support MySQL PDO?

Hi,

MySQL PDO support or not, not related with jomsocial. jomsocial running under joomla, so that must depending with joomla it self.

some users got issue with PDO, maybe this link can help:
docs.joomla.org/J3.x:Class_'PDO'_not_found

but for more support regarding PDO, please open new topic at:
forum.joomla.org/

Regards