Related to https://umod.org/community/backpacks/9741-nullreferenceexception-at-trymigratedata?page=1#post-1 The steps in that post fixed it.

(11:39:33) | Failed to run a 0.50 timer in 'Backpacks v3.1.0' (InvalidCastException: Null object cannot be converted to a value type.)
  at System.Convert.ChangeType (System.Object value, System.Type conversionType, System.IFormatProvider provider) [0x00029] in <437ba245d8404784b9fbab9b439ac908>:0 
  at System.Convert.ChangeType (System.Object value, System.Type conversionType) [0x0000c] in <437ba245d8404784b9fbab9b439ac908>:0 
  at Oxide.Core.Plugins.Plugin.Call[T] (System.String hook, System.Object[] args) [0x00008] in <ac41dd3599754d448b8c218b34645820>:0 
  at Oxide.Plugins.Backpacks+Backpack.Open (BasePlayer looter) [0x000df] in <320e78ea62354c23ab60674a80ee495c>:0 
  at Oxide.Plugins.Backpacks+<OpenBackpackChatCommand>c__AnonStorey3.<>m__0 () [0x00010] in <320e78ea62354c23ab60674a80ee495c>:0 
  at Oxide.Core.Libraries.Timer+TimerInstance.FireCallback () [0x00018] in <ac41dd3599754d448b8c218b34645820>:0​

Thank you