404: streamtoken not registered or valid

What has happened to Plotly? For at least 18 months I have been using it to display graphs of the performance of my central heating while I’m away but since about the 15 March 2017 it has only worked three times. The rest of the time I, like many others, am getting messages about “404: streamtoken not registered or valid” in the log. The only thing created are the graph axes. I though at first it was a problem with my Raspberry Pi but, having made changes, I am convinced it is not, especially as a search online reveals I am not alone. What is the problem, what is the fix?

This program has been so useful and simple to use I have no desire to have to move to another one with all the hassle involved.

Has this been logged as a problem? See After initial success, now plotly sets up chart, fails to accept data stream .

It seemed that something changed in Feb/March 2017.

Is anyone at Plotly listening?