setting fit options doesn't work with a parfor loop

I am performing a fit multiple times within a for loop. When I use a normal "for" loop, everything works fine. But when I use a "parfor" loop, I get an error related to setting the fit options. Below is a minimum working example. I am using Matlab R2018b.

% Generate some data
Npts = 50;
Ntime = 10;
tau = 10;
x = repmat( (1:Npts)',1,Ntime);
y = exp(-x/tau) + (rand(Npts,Ntime)-0.5)/10;

% Plot the data
figure;
plot(x(:,1),y(:,1),'-o')
title('Data for first time step')

% Fit options
ft = fittype('exp1');
fo = fitoptions( 'Method', 'NonlinearLeastSquares' );

% Pre-allocate the decay constant, tau
tau = NaN(1,Ntime);
parfor q = 1:Ntime
        
    % Perform the exponential fit at time step q
    fitresult = fit( x(:,q), y(:,q), ft, fo);
    
    % Save the decay constant, tau
    tau(q) = -1/fitresult.b;
    
end

[Walter Roberson]

Duplicates https://www.mathworks.com/matlabcentral/answers/491176-fit-options-in-a-parfor-loop