c# - "The input array was empty" ArgumentException when making a invoked cross thread call -

i have 2 separate threads , need call members other thread. via normal method of invoking. here's basic setup:

void foo() //on thread 1 {      if (this.invokerequired)           this.invoke(new action(foo2));      else           foo2(); }  void foo2(){/*do work*/} //accesses members on thread 2 

i'm getting error "argumentexception unhandled: input array empty". thing is, method i'm trying invoke has no parameters, , per documentation, shouldn't issue.

i tried replacing:

this.invoke(new action(foo2)); 

with

this.invoke(new action(foo2), null); 

(the documentation says if there no parameters, pass null, , i'm still getting same error)

here's top of stacktrace:

at system.windows.forms.control.marshaledinvoke(control caller, delegate method, object[] args, boolean synchronous) @ system.windows.forms.control.invoke(delegate method, object[] args)

so, says array (for parameters presume) empty, in fact correct because i'm calling method no parameters... what's catch here?