ninjatrader crashes after startup

[junkone]

everytime, i open NT, it crashes.
the logs shows this.

2021-10-30 20:02:45:936 ERROR: Strategy '245219647': unable to deserialize user data: There is an error in XML document (2, 2).
2021-10-30 20:02:46:998 *************** unhandled exception trapped ***************
2021-10-30 20:02:46:998 Object reference not set to an instance of an object.
2021-10-30 20:02:46:998 System.NullReferenceException: Object reference not set to an instance of an object.
at NinjaTrader.NinjaScript.NinjaScriptBase.SetState(S tate state)
at NinjaTrader.Gui.NinjaScript.StrategyRenderBase.Set State(State state)
at NinjaTrader.NinjaScript.NinjaScriptBase.Finalize()

i removed the xml under workspace folder hoping that it will get rid of any persisted data but still i cannot get NT to startup.
what needs to be done to get NT started?

[junkone]

i started from scratch again ie blanked the C:\Users\xx\Documents\NinjaTrader 8 folder. Now i find that i get a new error and crash when i load the indicators panel and it shows this message before crashing.
this message does not occur when i have the indicator pullbacksystem disabled but i cannot find anything wrong with this code. it used to work 2 days back properly.

which part of this code seems messed up as it does compile properly

[NinjaTrader_ChelseaB]

Hello junkone,

This typically indicates an error in the code of the strategy named 245219647.

Likely this is an xml error from not using the XmlIgnore() property on public variables that are not string, int, double, or enum.

https://ninjatrader.com/support/helpGuides/nt8/xmlignoreattribute.htm

What public variables are in your script? Are there public variables that do not have the XmlIgnore() attribute applied?