Logging into Plesk: ERROR: PleskMainDBException

[ThomasWales]

I've just come across this error, and unable to find the issue. Could someone advise.

I have followed this guide however no luck! http://kb.parallels.com/en/115602

ERROR: PleskMainDBException
DB query failed: Unknown error

0: common_func.php3:137
	db_query(string 'set names utf8')
1: common_func.php3:640
	reconnect()
2: common_func.php3:600
	db_connect()
3: auth.php3:134

Thanks

 

[McDonald1]

I have partially fixed this issue, but require further help.

It looks like a change was made to the firewall settings (I think this was done by .net microsoft patch)

I have manually added mysql-nt to the firewall ruleset, and this has allowed MySql to talk to the application. (Wordpress websites are now working)
However
I still get the same error when i try to log in to the control panel.
ERROR: PleskMainDBException
MySQL server has gone away

0: common_func.php3:637
reconnect()
1: common_func.php3:600
db_connect()
2: auth.php3:134

Is there a list of firewall rules that need to be in place to allow Plesk to work?