Apologies for the long post but I wanted to include as much detail as possible.
My setup is Pi3,Stretch,Nginx and owncloud10. I'm trying to setup owncloud in a subdirectory ie accessible by 192.168.xx.xx/owncloud. I've used the example nginx config file from https://doc.owncloud.org/server/10.0/admin_manual/installation/nginx_configuration.html for owncloud in a subdir of nginx and as suggested have added 'overwritewebroot' => '/owncloud', in config/config.php
When I access 192.168.xx.xx/owncloud the initial setup page displays correctly. However, when I enter the initial details and click Finish Setup I get a 404 Not Found error for 192.168.xx.xx/owncloud/index.php. On checking the /var/log/nginx/error.log I can see that the address for the index.php is incorrect, ie there is an extra owncloud directory:
*2 FastCGI sent in stderr: "Unable to open primary script: /var/www/owncloud/owncloud/index.php (No such file or directory)" while reading response header from upstream, client: 192.168.xx.xx, server: 192.168.xx.xx, request: "POST /owncloud/index.php HTTP/2.0", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.xx.xx"
Has anyone any ideas how I can sort this? If I remove the overwritewebroot then the initial owncloud setup page does not display correctly as none of the .css files load.