Firebird Client not Compatible with V3/V4 in same process

[Tony Valenti]

Hi All -

We have an application that needs to connect to multiple versions of Firebird.

We've found a bug where it seems the provider does not work correctly when using DLLs from two different versions.  We get an error like this:

FirebirdSql.Data.Common.IscException: 'Error loading plugin Engine13
Module C:\Users\Administrator\source\repos\TonyValenti\FirebirdSql.Bin\src\FirebirdSql.Bin.Test\bin\Debug\net9.0\win-x64\V4\plugins\Engine13 exists but can not be loaded'

Is there anyone I can work with to get this bug resolved?

[Jiří Činčura]

The "exists but can not be loaded" usually indicates some native dependency missing, like C++ redist.

OTOH using two Firebird versions in one process is very likely not going to work. Firebird creates some shared/global resources and these will collide when using from multiple instances/versions.

--
Mgr. Jiří Činčura
https://www.tabsoverspaces.com/

[Mark Rotteveel]

On 11/04/2025 09:33, Jiří Činčura wrote:
> The "exists but can not be loaded" usually indicates some native dependency missing, like C++ redist.
>
> OTOH using two Firebird versions in one process is very likely not going to work. Firebird creates some shared/global resources and these will collide when using from multiple instances/versions.
>

That could be solved by using only Firebird 4.0, and including the
engine12.dll of Firebird 3.0 in its plugins directory, and making
appropriate changes to its firebird.conf and/or databases.conf.

Mark
--
Mark Rotteveel