Log files full of service broker errors, but it works OK

Question

We have a C# web application that is using SQL dependency to expire cached query data. Although everything is working okay we are seeing a lot of errors being generated particularly in our production environment.
The first error messages is this:
Service Broker needs to access the master key in the database 'SubscriberManager'. Error code:32. The master key has to exist and the service master key encryption is required.
It shows up in both the server event log and the SQL server log files. I believe the actual content of the messages something of a red herring as I have created a database master key.
I have also tried
Recreating both the service master key and the database master key.
Made sure the database owner is sa.
Made sure the user account has permissions to create services, queues, procedures and subscribe query notifications
Made sure the broker is enabled
I have seen other people with similar errors whilst researching the issue but the error code almost always seems to be 25 or 26 not 32. I have been unable to find anything that tells me what these error codes mean so I'm not sure of the significance.
Also I am seeing a lot of errors like this:
The query notification dialog on conversation handle '{2FA2445B-1667-E311-943C-02C798B618C6}.' closed due to the following error: '-8490Cannot find the remote service 'SqlQueryNotificationService-7303d251-1eb2-4f3a-9e08-d5d17c28b6cf' because
it does not exist.'.
I understand that a certain number of these are normal due to the way that SqlDependency.Stop doesn't clean everything up in the database, but we are seeing thousands of these on one of our production servers.
What is frustrating as we have been using SQL notifications for several years now without issue so something must have changed in either our application or the server setups to cause this but at this point I have no idea what.
The applications are .net 4.0 MVC and WCF running on Windows 2012 servers calling SQL 2012 servers also running on Windows 2012.

Answer 1

Hi Mark,
1. for your question about possible memory pressure, if the used memory is below the Max Server Memory, then it's OK. If you have not set Max Server Memory, you should at least leave 4GB for your x64 system.
2. for your original question, I suggest you can check my actions below:
a. run this statement:
Select name, is_master_key_encrypted_by_server
from sys.databases
Where name =
'your_database_name'
if the value of "is_master_key_encrypted_by_server" equals to "0", it means the database does not have a encrypted master key.
b.if there is no encrypted master key, then the error may be hit by the "begin dialog conversation" statement (you can check your sql profiler trace to check".
"Service Broker dialog security lets your application use authentication, authorization, or encryption for an individual dialog conversation (or dialog). By default,
all dialog conversations use dialog security. When you begin a dialog, you can explicitly allow a dialog to proceed without dialog security by including the ENCRYPTION = OFF clause on the BEGIN DIALOG CONVERSATION statement. However, if a remote service binding
exists for the service that the conversation targets, the dialog uses security even when ENCRYPTION = OFF."
(http://msdn.microsoft.com/en-us/library/ms166036.aspx)
Workarounds can be disabling the dialog security (using encryption = off) or create a master key. You can find more information in about URL.