When you try to run PolyBase queries that cast a non-Unicode string column using a Unicode-only UTF8 collation (for example, Assamese_100_CI_AI_KS_SC_UTF8), you may receive the following error:
Conversion to non-Unicode character data types cannot be performed using a Unicode-only collation. Please use COLLATE clause to set a collation which is not Unicode-only.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
This issue is fixed in the following cumulative update for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and security fixes that were in the previous build. We recommend that you install the latest build for your version of SQL Server:
Learn about the terminology that Microsoft uses to describe software updates.