In a database restore operation process encountered as above error, went to Baidu to find the corresponding solution
The first one:
When restoring a full backup, in the reply state State where the restore with NORECOVERY is selected, the tail-log section is optional and depends on your specific needs. Tick "Close existing connection to target database", etc. when restoring log
Restore with Recvery in the reply state, the database can be used normally, if you still need to continue restoring the log, continue to choose NORECOVERY
A second method:
In the Restore interface, uncheck the end-of-log backup before the restore, and then tick overwrite the existing database (if you are a new database, or you will overwrite the original database)
SQL2012 Database restore failed System.Data.SqlClient.SqlError: Unable to execute backup LOG because there is currently no database backup