With Purity 4.1.x we introduced “User Session Logs” that requires passing a UserAgent string to the array in order log the details. For example on SE-PURE4 the below shows a logged request from the PureProviderConfig utility to setup the VSS connectivity to the FlashArray. The calls made from the VSS Provider are REST API calls which is noted as "Interface REST".
The VSS 1.0.0 Hardware Provider did not implement this requirement and therefore will fail to authenticate. A new version of the VSS Provider is required for any array that was upgraded from Purity 4.0.x to Purity 4.1.x . If an existing array connection was made using PureProviderConfig prior to upgrade these connections will need to be newly configured.
In a future version of Purity the VSS Provider will be removed from the Plugins section of the System tab and customers will need to download from the Pure Storage Community site.
If you run into any issues with VSS failing be sure to check the Purity version as this will most likely be the main problem.