I have my java application running as a linux Systemd service (Fedora
29 server).

My application perform a backup each day, but the process are throwing
an exception:

java.sql.SQLException: Unable to complete network request to host
"127.0.0.1". [SQLState:08006, ISC error code:335544721]
at org.firebirdsql.gds.ng.FbExceptionBuilder$Type$1.createSQLException(FbExceptionBuilder.java:498)
at org.firebirdsql.gds.ng.FbExceptionBuilder$ExceptionInformation.toSQLException(FbExceptionBuilder.java:454)
at org.firebirdsql.gds.ng.FbExceptionBuilder.toSQLException(FbExceptionBuilder.java:218)
at org.firebirdsql.gds.ng.wire.WireConnection.identify(WireConnection.java:331)
at org.firebirdsql.gds.ng.wire.FbWireDatabaseFactory.performConnect(FbWireDatabaseFactory.java:51)
at org.firebirdsql.gds.ng.wire.FbWireDatabaseFactory.serviceConnect(FbWireDatabaseFactory.java:45)
at org.firebirdsql.management.FBServiceManager.attachServiceManager(FBServiceManager.java:194)
at org.firebirdsql.management.FBBackupManager.backupDatabase(FBBackupManager.java:95)
at org.firebirdsql.management.FBBackupManagerBase.backupDatabase(FBBackupManagerBase.java:142)
at br.com.jjw.besser.retaguarda.database.DatabaseBackup.backup(DatabaseBackup.java:100)

What can be this? The 127.0.0.1 is not reacheable?