No alarm sound after update from CM 11 to CM 13 I recently updated my Samsung Galaxy S3 from Cyanogenmod 11.x to the latest 13.0. Despite some transitional issues, everything seemed fine.

Except that I almost overslept because the alarm was silent; only the vibration went off.

I have been through all the settings and combinations of modes (airplane mode, system profile, ...) -- volume is turned up everywhere but alarms are always silent. What do I have to do?

I use the system clock/alarm app.
As it turns out, the update skrewed up the link between alarms and ringtones resp. alarm sound. For me, the alarm app showed 17 instead of a sound name. 

You simply have to choose a new sound (or reselect the old one, as it where) and you have audible alarms back.