502 Bad Gateway nginx 'runtime_error' after update?

[Stephen_McMahon]

Hi all,
my VPS recently automatically upgraded Plesk to 12.0.18 & now I receive a 502 Bad Gateway nginx error on trying to login. I contacted my webhost, Webfusion but as this is a self-managed VPS I am responsible to fix this.

I have read & tried the following articles:

http://kb.odin.com/en/123735
http://kb.odin.com/en/118757
http://kb.odin.com/en/124377

On repairing the installation & received this error:

Cumulative upgrade and repair of APS controller database has been completed.
terminate called after throwing an instance of 'std::runtime_error'
what(): Unable to init lock manager shared memory file: Unable to create new lock manager shared memory storage. Please, try to restart sw-engine service as root.
/usr/local/psa/bootstrapper/pp12.0.18-bootstrapper/bootstrapper.sh: line 4471: 11008 Aborted $PRODUCT_ROOT_D/bin/sw-engine-pleskrun "$@"
Trying to reset database user password for 'apsc@'... done
terminate called after throwing an instance of 'std::runtime_error'
what(): Unable to init lock manager shared memory file: Unable to create new lock manager shared memory storage. Please, try to restart sw-engine service as root.
/usr/local/psa/bootstrapper/pp12.0.18-bootstrapper/bootstrapper.sh: line 4471: 11019 Aborted $PRODUCT_ROOT_D/bin/sw-engine-pleskrun "$@"

I attempted to run: /usr/local/psa/admin/bin/nginxmng --disable
and received this:

terminate called after throwing an instance of 'std::runtime_error'
what(): Unable to init lock manager shared memory file: Unable to create new
lock manager shared memory storage. Please, try to restart sw-engine service a
s root.
Aborted

And this is the relevant output from the error_log:

2015/05/18 16:30:16 [crit] 484#0: *27 connect() to unix:/var/run/sw-engine.sock failed (2: No such file or directory) while connecting to upstream, client: [my IP address], server: , request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/sw-engine.sock:", host: "[my VPS]:8443"

2015/05/18 16:37:03 [crit] 484#0: *29 connect() to unix:/var/run/sw-engine.sock failed (2: No such file or directory) while connecting to upstream, client: [my IP address], server: , request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/sw-engine.sock:", host: "[my VPS]:8443"


I asked Webfusion to attempt to restart the sw-engine as I do not have node access but this had no effect.

Any suggestions would be much appreciated.
Thanks,

Steve.