I use the older version on my server and helping a friend put his server togeather and working from scratch but as soon as I try to add SuperSurem it lets me go add everything in the UI but as soon as I click confirm it just errors out:

Failed to call hook 'CommandSaveProduct' on plugin 'ServerRewards v2.0.7' (InvalidCastException: Null object cannot be converted to a value type.)
at System.Convert.ChangeType (System.Object value, System.Type conversionType, System.IFormatProvider provider) [0x00019] in <f98723dd4586469db5213ec59da723ca>:0
at System.Convert.ChangeType (System.Object value, System.Type conversionType) [0x00007] in <f98723dd4586469db5213ec59da723ca>:0
at Oxide.Core.Plugins.Plugin.Call[T] (System.String hook, System.Object[] args) [0x00008] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Plugins.ServerRewards.IsOwnedOrFreeItem (BasePlayer player, System.Int32 itemID, System.UInt64 skinID) [0x00019] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.CreateItemElement (Oxide.Game.Rust.Cui.CuiElementContainer container, System.String parent, Oxide.Plugins.ServerRewards+Products+Item item, Oxide.Plugins.ServerRewards+UIUser user, System.Int32 balance) [0x00027] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.CreateItemsLayout (Oxide.Game.Rust.Cui.CuiElementContainer container, System.String parent, Oxide.Plugins.ServerRewards+UIUser user, Oxide.Plugins.ServerRewards+Products products) [0x002b3] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.CreateItems (Oxide.Game.Rust.Cui.CuiElementContainer container, Oxide.Plugins.ServerRewards+UIUser user) [0x00071] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.OpenStore (BasePlayer player) [0x0017c] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.CommandSaveProduct (ConsoleSystem+Arg arg) [0x000fb] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.ServerRewards.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x01f9b] in <c0ae817956ae4a3da97a36ac77a89a94>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d59b507fd76240e5b62228d0eae39b73>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d59b507fd76240e5b62228d0eae39b73>:0

oh then if you reload the addon to get out of the UI you cant even run /s

it uses data files. unload server rewards, remove the offending object, load it again. when reloading it writes the state to disk, overwriting any changes

hello, im having the same problem,  fresh install , under Oxide, installed the plugin , gave me permission, and type /s, that same error appears, i can giveme rp points, and i didnt understand what to do and witch is the offending objet, its a fresh install i couldnt open the ui to add items, ill apreciate any more detailed guidelines, thanks