During a Hyper-V host rescan, available VSS providers are enumerated via a VSS API query. Then, all VSS volumes for which those providers can be used are retrieved.
In some rare scenarios, the results from the VSS API query may be inaccurate. In such cases, the registry value in the solution can override this VSS API compatibility check and allow the user to select any available VSS provider. However, using that provider may still fail if it turns out that the VSS provider is not actually compatible.