Errors in the high level relational engine. Login failed

If you are getting a message similar to the one below while processing the Data Package:

Internal error: The operation terminated unsuccessfully. Errors in the high-level relational engine. The following exception occurred while the managed IDbConnection interface was being used: Login failed for user 'sa'.. Errors in the high-level relational engine.

or

Errors in the high-level relational engine. The following exception occurred while the managed IDbConnection interface was being used: Login failed for user 'sa'.

To resolve the problem:

1) [list](a) If you are creating a brand new data-package with a Relational data sourceand if you are not into figuring out the privileges mentioned above, then please select the following option to avoid the problem - "Best performance with less storage required". Now try to re-process the data package, normally this is all it takes to resolve the issue. 

What we did here is to instruct Analyzer to bypass the step to create a temporary database on the SQL server so it bypasses the error.

(b) If you are creating a brand new data-package with Excel/file data source -- TBD

2) If you are re-processing an existing data-package then please use SQL Management Studio to verify to see if the cube database's data source is still valid to connect to the source data. There are few cases where the password is missing for some reasons: