upgrade to 1.36.20 now can't connect to mysql

[electron]

Was working before last update.
Now localhost/zm shows

ZoneMinder Error

Unable to connect to ZM db using dsn mysql:host=localhost;dbname=zm

SQLSTATE[HY000] [2002] No such file or directory

ZoneMinder will retry connection in 23 seconds.

[Magic919]

Is it running? Can you connect manually?