Several users are concerned about whether Firebird 5 clients and servers can run on older Windows versions, such as Windows 7 32-bit.
The good news is, they can! But you need to install something first. Firebird 5 is made with a C++ compiler from Visual Studio 2022, so it needs Universal C Runtime (UCRT) to work properly.
If you are installing Firebird manually from zip archive or as embedded into your software, don’t miss this note from readme:
Installation may fail on older versions of windows up to Win 8.1 and Windows Server 2008 if the most recent security updates have not been installed. This will also affect users of the zip packs as the problem lies with runtime library dependencies of applications such as instclient and instsvc. If you do run into this problem you should consult the microsoft knowledge base article KB2999226 for more information on how to upgrade your version of windows to use the latest run time libraries.
Practically, download and install the fresh UCRT from this link.