Seaquel
SQL Server error code

SQL Server error 1488

SQL Server raises error 1488 at severity 16, which marks a problem with the query or data that you can correct.

Database "%.*ls" database is in single user mode which is incompatible with participating in database mirroring or in an availability group. Set database to multi-user mode, and retry the operation.
Msg1488
Severity16
Group1000–1999

Source: Database Engine events and errors