After revisiting a site that I have not accessed for a few weeks, I get this error.
ConfigStorageReadException: The configuration file "system.core" is not properly formatted JSON. Contents: <pre></pre> in ConfigFileStorage->read() (line 1041 of /home/rnetcouk/public_html/core/includes/config.inc).
This prevents access to any page on www.r-net.co.uk
I suspect it may have been triggered by insufficient space being allocated on shared host, but that is now fixed.