Seaquel
SQL Server error code

SQL Server error 5321

SQL Server raises error 5321 at severity 16, which marks a problem with the query or data that you can correct.

The '%ls' function is not allowed in the %S_MSG clause when the FROM clause contains a nested INSERT, UPDATE, DELETE, or MERGE statement.
Msg5321
Severity16
Group5000–5999

Source: Database Engine events and errors