Seaquel
SQL Server error code

SQL Server error 3016

SQL Server raises error 3016 at severity 16, which marks a problem with the query or data that you can correct.

Backup of file '%ls' is not permitted because it contains pages subject to an online restore sequence. Complete the restore sequence before taking the backup, or restrict the backup to exclude this file.
Msg3016
Severity16
Group3000–3999

Source: Database Engine events and errors