During the TC Disrupt hackathon in Berlin last weekend we tried to use the generate_origin_destination_cost_matrix method but failed with this error message:
Could you please have a look at the code and tell me whether or not we did something wrong?
Your code is correct. There is a bug in the current version of the API that is causing the json to be sent using single quotes instead of double quotes, and some tools (like this one apparently) are sensitive to that.
We have fixed this bug and the fix will be included in v1.3 which is likely to release in the next couple weeks.