OwnCloud is a community and enterprise-based file cloud sharing service, similar to Dropbox and looks like Google Drive.
Installation goes pretty smooth, until you go to edit your mail templates, and you can edit/save each one until you get to New User Email (HTML or PlainText) and you receive the “Could not create directory” error.
A look into the log file and you’ll see this:
mkdir(): Permission denied at /var/www/owncloud/apps/templateeditor/lib/mailtemplate.php#98
The Fix
You need to create a subdirectory custom theme directory called settings, and then a subfolder in settings named templates, then apply read/write permissions. I’m assuming your base directory is /var/www, adjust as needed.
mkdir /var/www/<owncloud install dir>/themes/<your theme dir>/settings
mkdir /var/www/<owncloud install dir>/themes/<your theme dir>/settings/templates
chown www-data. /var/www/<owncloud install dir>/themes/<your theme dir>/settings -R
chmod 766 /var/www/<owncloud install dir>/themes/<your theme dir>/settings/templates
After this you should be able to save your New User HTML or Plain Text email template.