Error in Multi-D Acquisition while connected to Matlab


I use Matlab to open and control a MM 1.4 GUI. I am attempting to switch from Matlab 2018b to 2020a to solve another, unrelated, compatibility issue. However, whenever I try to run a Multi-D acquisition I get an error stating:

“JSONArray initial value should be a string or collection or array”

This problem was the subject of a thread in the old forum but no fix was described:

I am writing to ask if anyone has, in the meantime, discovered a solution ?



This is caused by MM including and using a very old version of the org.json package. Matlab most likely brings a newer version with it, which ends up the one being used. Code from the acquisition engine written in Clojure makes the offending call and I have no idea how to fix that one. In 2.0 we moved org.json to and you should no longer have this issue. Any reason to stick to the unmaintained 1.4 rather than use 2.0?