not stacking anymore and get

o.reload StackSizeController
[Stack Size Controller] Reverting stack sizes to vanilla defaults.
Failed to call hook 'Unload' on plugin 'StackSizeController v4.1.3' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.StackSizeController.GetVanillaStackSize (ItemDefinition itemDefinition) [0x00000] in <c3469c2bbfcc462ca3aafccf5a50134f>:0

  at Oxide.Plugins.StackSizeController.RevertStackSizes () [0x00052] in <c3469c2bbfcc462ca3aafccf5a50134f>:0

  at Oxide.Plugins.StackSizeController.Unload () [0x0000d] in <c3469c2bbfcc462ca3aafccf5a50134f>:0

  at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000c8] in <c3469c2bbfcc462ca3aafccf5a50134f>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b76ec77c47d1449e92b2baab8603843d>:0

Unloaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote
[Stack Size Controller] Acquiring vanilla defaults file from official GitHub repo and overwriting; https://raw.githubusercontent.com/WouayNote/StackSizeController/master/vanilla-defaults.json
Loaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote

Unloaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote
[Stack Size Controller] Acquiring vanilla defaults file from official GitHub repo and overwriting; https://raw.githubusercontent.com/WouayNote/StackSizeController/master/vanilla-defaults.json
[raw.githubusercontent.com]
Loaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote

That part of the message is normal and says the plugin is loaded, If you get an error message check your config for errors, mine is working without fail for many years now. always check you json files with a validator.

pookins

Unloaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote
[Stack Size Controller] Acquiring vanilla defaults file from official GitHub repo and overwriting; https://raw.githubusercontent.com/WouayNote/StackSizeController/master/vanilla-defaults.json
[raw.githubusercontent.com]
Loaded plugin Stack Size Controller v4.1.3 by AnExiledDev/optimized by WouayNote

That part of the message is normal and says the plugin is loaded, If you get an error message check your config for errors, mine is working without fail for many years now. always check you json files with a validator.

I have checked this but when i set the amounts they dont change i have also used it for 2-3 years and just had this issue a few days back

Merged post

i get

[Stack Size Controller] Exception encountered during GetStackSize. Item: hat.wolf Ex:System.NullReferenceException: Object reference not set to an instance of an object
  at Oxide.Plugins.StackSizeController.GetVanillaStackSize (ItemDefinition itemDefinition) [0x00000] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.StackSizeController.GetStackSize (ItemDefinition itemDefinition) [0x00020] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

Failed to call hook 'SetAllStacksCommand' on plugin 'StackSizeController v4.1.2' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.StackSizeController.GetVanillaStackSize (ItemDefinition itemDefinition) [0x00000] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.StackSizeController.GetStackSize (ItemDefinition itemDefinition) [0x0018d] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.StackSizeController.SetStackSizes () [0x0005c] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.StackSizeController.SetAllStacksCommand (Oxide.Core.Libraries.Covalence.IPlayer player, System.String command, System.String[] args) [0x00086] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x010ae] in <ff9a3627ee424ae9b20e3ea4fb6f7dc3>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b76ec77c47d1449e92b2baab8603843d>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b76ec77c47d1449e92b2baab8603843d>:0

Merged post

resolved by reinstalling the server and all plugins