I'm trying to install QGis Server 3.4 on Windows. Apache says "500 Internal Server error" and if I execute
qgis_mapserv.fcgi.exe, I get this:
(something along the way "can't find entry point for procedure foo in dll bar")
I installed it via OSGeo4W, selecting Desktop->qgis-ltr v3.10.3-1 (which fires up nicely), Libs->fcgi v2.4.1-2, and Web->qgis-ltr-server v3.4.15-1
In case it's some use, here's my PATH:
C:\OSGeo4W64\bin;C:\OSGeo4W64\apps\qgis-ltr\bin;C:\OSGeo4W64\apps\grass\grass78\lib;C:\OSGeo4W64\apps\grass\grass78\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\WBem;c:\OSGeo4W64\apps\qt5\bin. Those grass references are about and old QGis Server 2.18 installation, which I totally wiped.