Server taking too long to start

Just got the Unifi UAP-AC-HD and am having trouble with the controller starting.

I downloaded the latest Unifi controller software (5.5.20).

I am running this on a mac...OS Sierra (10.12.6)

As per a lot of posts here the controller will not startup.  The UI shows this:

Initializing UniFi Controller ...
Starting UniFi Controller ...
Server taking too long to start...
Start-up failed.

The server.log shows this:

[2017-09-16 15:22:57,175] <launcher-ui> INFO  launcher - Initializing UniFi Controller ...

[2017-09-16 15:22:57,365] <launcher-monitor> INFO  launcher - Starting UniFi Controller ...

[2017-09-16 15:22:58,399] <launcher> INFO  system - ======================================================================

[2017-09-16 15:22:58,400] <launcher> INFO  system - UniFi 5.5.20 (build atag_5.5.20_9565 - release) is started

[2017-09-16 15:22:58,400] <launcher> INFO  system - ======================================================================

[2017-09-16 15:22:58,403] <launcher> INFO  system - BASE dir:/Applications/UniFi.app/Contents/Resources

[2017-09-16 15:22:58,408] <launcher> INFO  system - Current System IP: 192.168.0.20

[2017-09-16 15:22:58,571] <launcher> INFO  system - Hostname: Shanes-MacBook-Pro.local

[2017-09-16 15:22:58,734] <launcher> INFO  db     - waiting for db connection...

[2017-09-16 15:22:59,237] <launcher> INFO  db     - Connecting to mongodb://127.0.0.1:27117

[2017-09-16 15:23:00,320] <launcher> INFO  db     - *** Factory Default *** Database exists. Drop it

[2017-09-16 15:23:00,331] <launcher> INFO  db     - waiting for db connection...

[2017-09-16 15:23:02,474] <launcher> INFO  db     - Connecting to mongodb://127.0.0.1:27117

[2017-09-16 15:23:02,490] <launcher> INFO  stat   - *** Factory Default *** Stat Database exists. Drop it

[2017-09-16 15:23:03,594] <launcher> WARN  discover - unable to join multicast group 233.89.188.1 on awdl0 (/fe80:0:0:0:bc69:85ff:fe33:6786%awdl0)

[2017-09-16 15:23:03,717] <launcher> INFO  webrtc - WebRTC library version: EvoStream Media Server (www.evostream.com) build v1.0.20 - Gladiator - (built for MacOSX-10.9-x86_64 on 2017-06-15T19:07:21.000) OpenSSL version: 1.0.2k usrsctp version: d350f4ec3e9bc0ed compiled on machine: Darwin jenkins-slave-2.local 13.4.0 Darwin Kernel Version 13.4.0: Mon Jan 11 18:17:34 PST 2016; root:xnu-2422.115.15~1/RELEASE_X86_64 x86_64

[2017-09-16 15:29:58,207] <launcher-monitor> ERROR launcher - Server taking too long to start...

[2017-09-16 15:29:58,212] <launcher-ui> ERROR launcher - Start-up failed.

The mongod.log is quite long however does not appear to have any obvious errors.

As per other posts I have tried downgrading to java 6.  This did not make any difference.

At a bit of a loss here so any help appreciated.