My advice is to back up the master key no matter what.  Hypothetically, the server dies and needs to be rebuilt from scratch.  You install the SQL instance, restore the...

I have not seen that exact error, but my guess is that the error isn't being thrown by the SQL Server installer,but being thrown by Windows.  My GUESS is that...

That is how a firewall is designed though.  There are no "shortcuts" with security.

The ONLY other way you can set that up is to allow applications through the firewall instead...

CASE statement.  I'm not entirely sure where you are running the query, but basically do a check if SYSDATETIMEOFFSET() > Daylight savings start date AND if SYSDATETIMEOFFSET() < Daylight savings...

Did you restore the encryption keys using the SSRS configuration tool?  Without that, it won't be able to decrypt any encrypted data.

I would recommend checking out this post:

https://stackoverflow.com/questions/46876442/ssrs-migration-from-2008-to-2016/46879292#46879292

and make sure...

The post is very confusing.  Did you do an inplace upgrade or did you do a migration?  I am not sure what an "inplace migration" is.  I am also confused...

I think if you are stuck on SQL Server 2012, you are going to need to use a CASE statement to handle daylight savings time.

If you can upgrade to 2016,...

To add to Frederico_fonseca's response - when I hit snags like that, my first step is to take the innermost portion of the troublesome query section and break it out. ...

For something like that, you will need to use dynamic SQL.

Be careful using it though as if it is not designed carefully and with proper safeguards, it is easy to...

That is weird that running it in series causes the block as well...

even stranger that running package 1 to call 1 copy of package 2 makes things run successfully.

I would capture as much data as I can that makes sense.  A timestamp of the import is something I try to capture in the staging and historical tables because...

That is a big "it depends" question.  OLAP is used for reporting and analytics.  OLTP is used for transactional data.

If you have a bunch of data used for application purposes,...

SPID -2 is an orphaned DTC transaction:

https://www.sqlskills.com/blogs/paul/disaster-recovery-101-dealing-with-negative-spids-2-and-3/

Another good read on SPID -2:

http://www.eraofdata.com/sql-server/troubleshooting-sql-server/orphaned-msdtc-transactions-2-spids/

So something is starting a distributed transaction and SQL is uncertain on the state of that distributed transaction.

Also, how...

My opinion (others may disagree), I try not to denormalize reporting data unless some of the data is going to be used by multiple reports.  I try to reduce the...

So it isn't the client then... I am wondering if it could be the mail server.

If it was consistent it would be easier to figure out.   If it showed up...