Previewing my project presents a blank sceen and http error 500

They should be in the Apache error log. If you cannot get those yourself, you should be able to request them from your provider.

Hi Tom,
My ISP support checked apache's error log yesterday and there weren't any errors being logged (normally this would be the case with a server 500 error, but in this case it's not). They've just recreated the server 500 error, whilst running a tail on apache's error log, but nothing is being logged. That said, when they recreated the server 500 error, this error log was written to: public_html/xerte/error_logs/debug.log (Copy of today's log is attached - I've anonymised my domain name)
Hope this helps.
Richard

Hi Tom,
I've arranged with my ISP to reinstate xerte from a previous site backup and will catch up from there.
Thanks again for you help and interest.
Regards
Richard

Hi Richard,

Very strange that the erro 500 is not logged in the Apache error log. The error_log/debug.log is just that. A debug log that is activated when $development is set to true in config.,php. It (regrettably) does not log the error 500 cause. With no further information, there is not much I can do.

Tom