Seaquel
SQL Server error code

SQL Server error 526

SQL Server raises error 526 at severity 16, which marks a problem with the query or data that you can correct.

%ls of XML types constrained by different XML schema collections and/or DOCUMENT/CONTENT option is not allowed. Use the CONVERT function to run this query.
Msg526
Severity16
Group0–999

Source: Database Engine events and errors