Error Variable in a parfor cannot be classified - Parfor

I am trying to convert my code over to run with parfor. However there is an error "The variable KG in a parfor cannot be classified". I have search around on the website and have read people with similar problems, but none of those answers seem to fix my problem. My code is as follows. (Nnod is a number, Mnod and Melem are arrays). I appreciate the help.

Ndofs=Nnod;
KG=sparse(Ndofs,Ndofs);
FG=zeros(Ndofs,1);
parfor i=1:Nelem
    Ke = Kelem(i,Mnod,Melem);
    Fe = Felem(i,Mnod,Melem);
    
    nod1 = Melem(i,2);
    nod2 = Melem(i,3);
    nod3 = Melem(i,4);
    
    dofs = [nod1,nod2,nod3];
    
     for L=1:length(dofs)
         for m=1:length(dofs)
             KG(dofs(L),dofs(m))=KG(dofs(L),dofs(m))+Ke(L,m);
         end
         FG(dofs(L))=FG(dofs(L))+Fe(L);
     end    
end

Answer 1

[Srivardhan Gadila]

The code itself displays the following warnings before executing it:

Try to fix these warnings before executing the code & then refer to the documentation of Nested for-Loops: Requirements and Limitations.

You may also refer to the relevant pages at Help Center: "The variable in a parfor cannot be classified" & already answered MATLAB Answers.