There are multiple Firebird instances on the server: FB25, FB3, and FB5. Each instance is assigned a dedicated port and an appropriate service name. When using a third-party application to perform a restore, it connects to the server via a TCP connection using the connection string localhost/3056:some_path_to_database.

At the end of the restoration process, the following error message appears:

Unable to complete network request to host "localhost". Error reading data from the connection.

Additionally, there is a record in the firebird.log file:

XNET error: XNET server initialization failed. Probably, another instance of the server is already running.

The resulting database file appears to be corrupted, and subsequent gfix -v -full ... shows:

Number of record level errors : 18722