The GAC probe only ever looked for the exact folder of the requested version.
For about a hundred assemblies the .NET Framework 4.7.2/4.8 reference assemblies
carry a higher version than the implementation ever installed in the GAC
(System.IO.Compression is 4.2.0.0 against 4.0.0.0 in the GAC, System.Runtime is
4.1.2.0, ...), because out-of-band packages shipped those versions and the ref
assemblies had to keep up. The runtime hides this behind assembly unification;
without an equivalent, every reference to one of them was reported as
unresolvable.
Matching on the major version keeps assemblies apart that share a name but are
different products, e.g. Microsoft.Build.Framework 4.0.0.0 and 15.x.
Assisted-by: Claude:claude-opus-5:Claude Code
Siegfried Pammer