matlabFunction randomly throws errors

As a replacement for global variables, I use matlabFunction to write numbers and variables to a function, which I then access as if it were a global variable. However, matlabFunction is not very reliable. At random moments it will fail and throw the following error:

Error using sym/matlabFunction>writeMATLAB (line 431)
Failed to create file TEST.m: Invalid argument.

Error in sym/matlabFunction (line 179)
  g = writeMATLAB(funs,file,varnames,outputs,body, opts.Optimize, opts.Sparse);

I created this simple code to reproduce the problem:

for i=1:100
  try
      matlabFunction(sym(5),'File','TEST');
  catch
      disp(i)
  end
end

For me this code generally displays 3 or 4 random numbers between 1 and 100, indicating 3 or 4 errors in running 100 iterations of the exact same code. Some days it may be less and I might require 1000 iterations to produce 4 errors.

As a workaround, I simply try to call the function again:

for i=1:10
  try
      matlabFunction(sym(0),'File','get_xf');
      break
  catch
      disp('matlabFunction error')
      continue
  end
end

In theory, this workaround is not 100% safe. In practice, however, it suffices.

The question is, what is causing these errors and how do I prevent them? Not sure if it's relevant, but I use version R2017a under an academic license.

Kindest regards,

Jurriën

Answer 1

[Jurriën]

I contacted Mathworks support and they suggested a number of reasons that might cause this kind of error. It turns out it was caused by Dropbox. I run my script in a folder that is synced, and this syncing may prevent Matlab from writing a function and thus throw an error.

So for anyone reading this and having the same issue: don't save your scripts in a synced folder.