did you check the errorlog files to determine who disabled / stopped the default trace ?

sure. if we remove the "execute as" clause, they can see the sqlplan.
However, the sproc is intended to be used by a user account that only has exec auth...

Even created and executed by a sysadmin, it does throws the same error.

Also tested grant showplan to public .... same error at showplan time 🙁

- one of the things you must configure with sqlserver is the number of errorlog files to keep after startup. (now you get why)
- I would have guessed it...

Any extra information in the SQLServer errorlog ?

SOLUTION:

For DBMirroring to be able to use KERBEROS,
you need to register an SPN for the service account to the Endpoint port number ! 

I finally got this to work lowering AUTHENTICATION settings

..;   FOR DATA_MIRRORING (
         ROLE = ALL,
         AUTHENTICATION = WINDOWS NEGOTIATE ,
         ...

It depends: https://www.brentozar.com/sql/sql-server-san-best-practices/

it depends on the nature of the data.
If that data is to sensitive ( names / Social numbers / ... ) they could refuse the auth.
IMHO in all...

I liked the article until I read the content of the DTU calculation webpage. 
At least the first 2 paragraphs are yours.

You can copy the data/tables from to your primary mdf file.

How? That depends on your current configuration.
If you post your databases DDL (create database statement) we may...

it actually performs the collation translation, and materializes that data in tempdb,  so .... yes.

The only decent way around it, is to create a new db and its...