Callback error after multiple runs


I have a callback that uses a dcc.Dropdown to save data to a dcc.Store, then displays it in a datatable. Much like the example provided.

Initially, all works great but after adding and removing the same item from my dropdown maybe 3 or 4 times I eventually get an error.

“Callback error updating” but with no further info.

The code is long so i’ve not posted it, but how would i investigate the cause of the error?