I would focus upon "Encryption not supported on the client" message, where the "client" is Server A. Inspect ServerA's system event log (at very least, during the restart of the...

I am unsure what your application's "update conflict process" does - are you referring to SQL Server's internal process? If the application's, how does its code handle a Msg 3960,...

Was SQL Server raising an exception, assertion, or high severity error to its errorlog at the time?

To receive an accurate and quick answer, please offer us a script that creates tables, inserts sample data, and shows the SQL attempted. Also offers us the expected results. Use...

Hard to say without the complete verbatim error message. Connection failures go through Winsock, and if it raises an error (such as Network Name Not Found) the problem does not...

Can't help you much on the specifics in their current state. But has the required reboot been done? If unsure, filter the system event log by event ID 6009. And...

I don't have a list. However, https://support.microsoft.com/en-us/search?query=kbhotfixrollup%20%22database%20mirroring%22 should get you close to an answer.

I also suggest you very carefully review https://support.microsoft.com/en-us/kb/2729953, consider there are at least two issues...

Ensure SQL Server's Facets is configured to audit login failures. Look at the SQL Server errorlog for the user's account, at the time when the login failed error is raised....

Error is likely being raised due to an implicit cursor conversion - see https://msdn.microsoft.com/en-us/library/ms131660.aspx. Consider URL's discussion of SQL_SUCCESS_WITH_INFO and

The application can determine what type of cursor is now...

Instead of rebuilding, see whether UPDATE STATISTICS, by itself, improves performance.

Temporary tables have session-level scope. A new connection will be unable to see temporary objects created in another connection. It is possible to use global temporary tables, but I would...

Open

SQL Server Configuration Manager | SQL Server Network Configuration | Protocols for <InstanceName>

and verify TCP/IP protocol is Enabled. Enable it if not enabled, and restart SQL Server. Double...

EXECUTE syntax (https://msdn.microsoft.com/en-us/library/ms188332.aspx) states

Key phrase being "in the module", where "module" refers to an object in sys.all_sql_modules. In contrast to...

Implicit conversion due to data type precedence, forcing a scan (AKA Make sure data types match). Avoidable uses of temp tables, when a CTE or a derived table is equivalent...

COPY ONLY is useful when differential backups are taken. A differential backup cannot be restored unless its full backup is restored first. A COPY ONLY backup will not change the...