I am thinking of using Firebird with my application. I want to know what the firebird.msg file is used for. Is it an optional or mandatory file to include in your application installer package?
firebird.msg contains the actual error messages of Firebird. When an error occurs, Firebird only sends the error code and message parameters. The client library then looks up the actual error message text in this file.
Without the presence of this file (for Firebird 2.5 and earlier in a folder one level above the fbclient.dll (or similar libraries), for Firebird 3 and later in the same folder) the errormessage will only report that it couldn't find firebird.msg and the error number.
So you don't really need it, but if you need or want to package the Firebird client or embedded libraries and if you need or want meaningful error messages from Firebird, then you should include it.