I used to have OwnCloud version 5.x installed from ReadyNAS Xtras and it functioned well, although I was disapponted that it is out-dated. With recent update to firmware 6.1.6 I have noticed that update for OwnCloud 6.0.0 is also available from Poussin, so I updated it.
The result of update was a blank screen if I follow URL: https://<ready nas ip>/owncloud/index.php I restarted ReadyNAS, I removed OwnCloud, deleted the OwnCloud folder and added OwnCloud app again. The result is still the same: blank page (with empty HTML source)
I do not have any other applications installed, cause OwnCloud is all I need. Please help me to undestand or troubleshoot this problem. Maybe I'm missing some dependencies? Installation of PHP from Poussin didn't help me. I downloaded the log-files from ReadyNAS console, but couldnt find any trace of error or exception related to OwnCloud and why do i see just a blank page.
I found the reason of my problem. It is related to this issue: https://github.com/owncloud/core/issues/6351 Unfortunately the only way to solve it at the moment was to get SSH root access to ReadyNAS.
I modified /etc/php5/conf.d/20-xcache.ini file, the line related to variable cache:
xcache.var_size = 32M
Restarted Apache service:
/etc/init.d/apache2 restart
And then I was able to continue with OwnCloud 6.0.0 setup.
Hope this hint will help others who may enconter the same problem.
