Seaquel
SQL Server error code

SQL Server error 978

SQL Server raises error 978 at severity 14, which marks a problem with the query or data that you can correct.

The target database ('%.*ls') is in an availability group and is currently accessible for connections when the application intent is set to read only. For more information about application intent, see SQL Server Books Online.
Msg978
Severity14
Group0–999

Source: Database Engine events and errors