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SQL Server error code

SQL Server error 3159

SQL Server raises error 3159 at severity 16, which marks a problem with the query or data that you can correct.

The tail of the log for the database "%ls" has not been backed up. Use BACKUP LOG WITH NORECOVERY to backup the log if it contains work you do not want to lose. Use the WITH REPLACE or WITH STOPAT clause of the RESTORE statement to just overwrite the contents of the log.
Msg3159
NameLDDB_LOGNOTBACKEDUP
Severity16
Group3000–3999

What it means

In most cases, under the full or bulk-logged recovery models, SQL Server requires that you back up the tail of the log to capture the log records that have not yet been backed up. A log backup taken of the tail of the log just before a restore operation is called a tail-log backup.

Source: Database Engine events and errors