This post is mostly for me, just a FYI.

Every single time that I upgrade my Yireo Magebridge for Joomla and Magento I get this error:

The webshop is currently not available. Please come back again later.

And every single time, I scratch my head wondering how I fixed this error the last time I upgraded Magebridge.  So here are the instructions for me so I don’t waste time looking for this solution again:

The problem is with the magebridge.php file located in the magento subfolder.  You need to change the permissions back to 644.