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src/Workspaces/Remote/Core/Storage/RemotePersistentStorageLocationService.cs

@@ -33,6 +33,11 @@ public static void UpdateStorageLocation(SolutionId id, string storageLocation)
         {
             lock (_gate)
             {
+                // We can get null when the solution has no corresponding file location
+                // in the host process.  This is not abnormal and can come around for
+                // many reasons.  In that case, we simply do not store a storage location
+                // for this solution, indicating to all remote consumers that persistent
+                // storage is not available for this solution.
                 if (storageLocation == null)
                 {
                     _idToStorageLocation.Remove(id);