The perils of "one-click" installations:
I noticed that the Synology diskstation had a message on upgrade to Moodle 2.7 from the previous 2.4. Happliy clicked on yes. After a screen or two saying software being downloaded it stopped. No messages. But the Moodle was gone! It just brought the dreaded "Can not be found" message of Apache. The (web-based) logs had a message "Upgrade failed" or something similar, but not more.
After some tedious searching I believe that the upgrade script of DSM must have exited at a _warning_ the Moodle upgrade script brought: It complained that PHP module php5_intl is missing. Created a soft link moodle in the DocumenRoot to kick the Moodle upgrade script in the browser and it took me through the usual series of screens and finished the upgrade.
Demonstrates how fragile these one-click things are.