Submitted by: @mrotteveel

Restoring (not replacing) a database which already exists crashes gbak, or - when running through the service manager - the Firebird server process.

Steps to reproduce:

From ISQL:

create database 'd:\temp\restoretest.fdb' user sysdba password 'masterkey';

From command prompt:
gbak -b D:\temp\RESTORETEST.FDB D:\temp\restoretest.fbk -user sysdba -password masterkey

Replace works fine:
gbak -replace D:\Temp\RESTORETEST.fbk D:\Temp\RESTORETEST.FDB -user sysdba -password masterkey
gbak -replace -service localhost:service_mgr D:\Temp\RESTORETEST.fbk D:\Temp\RESTORETEST.FDB -user sysdba -password masterkey

But using simply create crashes either gbak or Firebird:

Crashing gbak (**after displaying the error message**):
gbak -create D:\Temp\RESTORETEST.fbk D:\Temp\RESTORETEST.FDB -user sysdba -password masterkey

This gives the error output:
"""
gbak: ERROR:database D:\Temp\RESTORETEST.FDB already exists. To replace it, use the -REP switch
gbak:Exiting before completion due to errors
"""

And then Windows displays the "Firebird SQL Server has stopped working" message (meaning gbak crashed, see also CORE5691)

Crashing Firebird server process:
gbak -create -service localhost:service_mgr D:\Temp\RESTORETEST.fbk D:\Temp\RESTORETEST.FDB -user sysdba -password masterkey

This gives the error output:
"""
gbak: ERROR:Error reading data from the connection.
gbak:Exiting before completion due to errors
"""

The crash of Firebird server is also reproducible with the Jaybird test org.firebirdsql.management.TestBackupManager.testBackupReplace().

Commits: a48f18f